Compressible Knitted Adjuncts with Surface Features

ABSTRACT

Adjuncts for use with a surgical stapler are provided. In one exemplary embodiment, an adjunct can include a first knitted layer, a second knitted layer, and a plurality of recesses that extend into and defined within the second knitted layer. The plurality of recesses can be arranged in a predefined pattern that coincides with a plurality of attachment features extending outward from a top surface of a cartridge such that each recess of the plurality of recesses is configured to engage with at least a portion of at least one attachment feature to form a friction fit therebetween to thereby retain the adjunct on the cartridge prior to staple deployment. Stapling assemblies for use with a surgical stapler are also provided.

FIELD

Compressible knitted adjuncts and methods of using the same areprovided.

BACKGROUND

Surgical staplers are used in surgical procedures to close openings intissue, blood vessels, ducts, shunts, or other objects or body partsinvolved in the particular procedure. The openings can be naturallyoccurring, such as passageways in blood vessels or an internal organlike the stomach, or they can be formed by the surgeon during a surgicalprocedure, such as by puncturing tissue or blood vessels to form abypass or an anastomosis, or by cutting tissue during a staplingprocedure.

Some surgical staplers require a surgeon to select the appropriatestaples having the appropriate staple height for the tissue beingstapled. For example, a surgeon could select tall staples for use withthick tissue and short staples for use with thin tissue. In someinstances, however, the tissue being stapled does not have a consistentthickness and, thus the staples cannot achieve the desired firedconfiguration at each staple site. As a result, a desirable seal at ornear all of the stapled sites cannot be formed, thereby allowing blood,air, gastrointestinal fluids, and other fluids to seep through theunsealed sites.

Further, staples, as well as other objects and materials that can beimplanted in conjunction with procedures like stapling, generally lacksome characteristics of the tissue in which they are implanted. Forexample, staples and other objects and materials can lack the naturalflexibility of the tissue in which they are implanted, and therefore areunable to withstand the varying intra-tissue pressures at theimplantation site. This can lead to undesirable tissue tearing, andconsequently leakage, at or near the staple site.

Accordingly, there remains a need for improved devices and methods thataddress current issues with surgical staplers.

SUMMARY

Adjuncts for use with a surgical stapler are provided. In one exemplaryembodiment, an adjunct includes a first knitted layer, a second knittedlayer, and a plurality of recesses. The first knitted layer can havefirst fibers and it can extend from a first top surface to a firstbottom surface with the first top surface defining at least a portion ofa tissue-contacting surface of the adjunct. The second knitted layer canhave second fibers and it can extend from a second top surface to asecond bottom surface with the second top surface defining at least aportion of a cartridge-contacting surface of the knitted adjunct. Theplurality of recesses can extend into and be defined within the secondknitted layer, and the plurality of recesses can be arranged in apredefined pattern that coincides with a plurality of attachmentfeatures extending outward from a top surface of a cartridge such thateach recess of the plurality of recesses is configured to engage with atleast a portion of at least one attachment feature to form a frictionfit therebetween to thereby retain the adjunct on the cartridge prior tostaple deployment.

In some embodiments, at least one of the first fibers and the secondfibers can be multifilament fibers.

The spacer fibers can have a variety of configurations. For example, insome embodiments, the spacer fibers can be intertwined with andextending between the first and second knitted layers to thereby connectthe layers together. In other embodiments, the spacer fibers can bemonofilament fibers.

In some embodiments, each recess of the plurality of recesses can beconically shaped.

Stapling assemblies for use with a surgical stapler are provided. In oneexemplary embodiment, a stapling assembly includes a cartridge, aplurality of staples, and a knitted adjunct. The cartridge extends froma top surface to a bottom surface that is opposite the top surface. Thetop surface can be a tissue-facing surface with a plurality ofattachment features projecting therefrom. The plurality of staples aredisposed within the cartridge and can be configured to be deployed intotissue. The knitted adjunct is configured to be releasably retained onthe cartridge such that the adjunct can be attached to tissue by theplurality of staples in the cartridge. The adjunct can include first andsecond knitted outer layers formed of fibers, and spacer fibersintertwined with and extending between the first and second knittedouter layers to thereby connect the layers together. The second knittedouter layer can have a plurality of preformed recesses defined therein,and each recess can be configured to receive and engage at least aportion of at least one extension feature of the plurality of attachmentfeatures to thereby retain the adjunct on the cartridge prior to stapledeployment.

The extensions can have a variety of configurations. For example, insome embodiments, each extension feature can have a conical-shape with afirst maximum diameter, and each recess can have an invertedconical-shape with a second maximum diameter that is less than the firstmaximum diameter. In other embodiments, each extension feature can havea conical-shape with a first maximum diameter and each recess can havean inverted conical-shape with a second maximum diameter that is greaterthan the first maximum diameter.

In some embodiments, at least one recess of the plurality of recessescan have a perimeter defined by a melted portion of the fibers of thesecond knitted outer layer. In other embodiments, at least one recess ofthe plurality of recesses can have a perimeter defined by knitted fibersof the second knitted outer layer. In some embodiments, at least onerecess of the plurality of recesses can have a minimum diameter that isless than a diameter of a staple leg of at least one staple of theplurality of staples. In other embodiments, at least one recess of theplurality of recesses can have a maximum diameter that is greater than amaximum diameter of at least one extension feature.

In some embodiments, the fibers of at least one of the first outerknitted layer and second outer knitted layer can be multifilamentfibers.

In some embodiments, the spacer fibers can be monofilament fibers.

In another exemplary embodiment, a stapling assembly for use with asurgical stapler includes a cartridge and a knitted adjunct. Thecartridge has a plurality of conically shaped projections coupled to andextending outward therefrom. The knitted adjunct is configured to bereleasably retained on the cartridge such that the adjunct can beattached to tissue by a plurality of staples disposed within thecartridge. The knitted adjunct includes a first knitted layer, a secondknitted layer, spacer fibers, and a plurality of conically shapedrecesses. The first knitted layer has first fibers and the first knittedlayer extends from a first top surface to a first bottom surface withthe first top surface defining at least a portion of a tissue-contactingsurface of the adjunct. The second knitted layer has second fibers andthe second knitted layer extends from a second top surface to a secondbottom surface with the second top surface defining at least a portionof a cartridge-contacting surface of the adjunct. The spacer fibers areintertwined with the first and second fibers to connect the firstknitted layer with the second knitted layer. Portions of the spacerfibers extend between the first and second layers in a generallycolumnar configuration. The plurality of conically shaped recessesextend into and are defined within the second knitted layer, and eachrecess can be configured to receive and engage at least a portion of atleast one conically shaped projection of the plurality of conicallyshaped projections to thereby retain the adjunct on the cartridge priorto staple deployment.

The recesses can have a variety of configurations. For example, in someembodiments, each recess of the plurality of recesses can have atapering diameter that decreases as the recess extends into the secondknitted layer. In other embodiments, at least one recess of theplurality of recesses can have a perimeter defined by a melted portionof the second fibers. In some embodiments, each recess of the pluralityof recesses can have a perimeter defined by knitted second fibers. Inother embodiments, each recess of the plurality of recesses can have aminimum diameter that is less than a diameter of a staple leg of each ofthe plurality of staples.

In some embodiments, at least one of the first fibers and the secondfibers can be multifilament fibers.

In some embodiments, the spacer fibers are monofilament fibers.

BRIEF DESCRIPTION OF THE DRAWINGS

This invention will be more fully understood from the following detaileddescription taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 is a perspective view of one exemplary embodiment of aconventional surgical stapling and severing device;

FIG. 2A is a top view of a staple cartridge for use with the surgicalstapling and severing device of FIG. 1;

FIG. 2B is a side view of the staple cartridge of FIG. 2A;

FIG. 2C is a perspective view of a portion of a tissue contactingsurface of the staple cartridge of FIG. 2A;

FIG. 3 is a side view of a staple in an unfired (pre-deployed)configuration that can be disposed within the staple cartridge of thesurgical cartridge assembly of FIG. 2A;

FIG. 4 is a perspective view of a knife and firing bar (“E-beam”) of thesurgical stapling and severing device of FIG. 1;

FIG. 5 is a perspective view of a wedge sled of a staple cartridge ofthe surgical stapling and severing device of FIG. 1;

FIG. 6 is a longitudinal cross-sectional view of an exemplary embodimentof a surgical stapling assembly having a compressible knitted adjunctattached to a top or deck surface of a staple cartridge;

FIG. 7 is a partial-schematic illustrating the adjunct of FIGS. 6A-6B ina tissue deployed condition;

FIG. 8A is a perspective view of an exemplary embodiment of a staplingassembly having a compressible knitted adjunct releasably retained on astaple cartridge;

FIG. 8B is a cross-sectional view of the portion of the staplingassembly of FIG. 8A taken at line 8B-8B;

FIG. 9A is a perspective view of another exemplary embodiment ofcompressible knitted adjunct;

FIG. 9B is a cross-sectional view of the adjunct of FIG. 9A taken atline 9B-9B;

FIG. 10A is a perspective view of another exemplary embodiment of astapling assembly having a compressible knitted adjunct releasablyretained on a staple cartridge;

FIG. 10B is a top view of the stapling assembly of FIG. 10A;

FIG. 10C is a cross-sectional view of the stapling assembly of FIG. 10Btaken at line 10C-10C;

FIG. 10D is a cross-sectional view of the stapling assembly of FIG. 10Btaken at line 10D-10D;

FIG. 11A is a perspective view of another exemplary embodiment ofcompressible knitted adjunct;

FIG. 11B is a cross-sectional view of the adjunct of FIG. 11A taken atline 11B-11B;

FIG. 12 is a perspective view of another exemplary embodiment ofstapling assembly having a compressible knitted adjunct;

FIG. 13A is a cross-sectional view of another exemplary embodiment of astapling assembly having a compressible knitted adjunct releasablyretained on a staple cartridge;

FIG. 13B is a cross-sectional view of the compressible knitted adjunctand staple cartridge of FIG. 13A in a detached configuration prior tobeing releasably retained;

FIG. 14A is a cross-sectional view of an exemplary embodiment of acompressible knitted adjunct in an uncompressed state;

FIG. 14B is a cross-sectional view of the adjunct of FIG. 14A in a firstcompressed state;

FIG. 15A is a cross-sectional view of an exemplary embodiment of acompressible knitted adjunct in an uncompressed state;

FIG. 15B is a cross-sectional view of the adjunct of FIG. 15A in a firstcompressed state;

FIG. 16A is a cross-sectional view of an exemplary embodiment of acompressible knitted adjunct in an uncompressed state;

FIG. 16B is a cross-sectional view of the adjunct of FIG. 16A in a firstcompressed state;

FIG. 17A is a cross-sectional view of an exemplary embodiment of acompressible knitted adjunct in an uncompressed state;

FIG. 17B is a cross-sectional view of the adjunct of FIG. 17A in a firstcompressed state;

FIG. 18A is a side view of an exemplary embodiment of a compressibleknitted adjunct having reinforcing knots;

FIG. 18B is a bottom view of the knitted adjunct of FIG. 18A;

FIG. 19A is a side view of an exemplary embodiment of a compressibleknitted adjunct without reinforcing knots;

FIG. 19B is a bottom view of the knitted adjunct of FIG. 19A;

FIG. 20 is a cross-sectional view of another exemplary embodiment of acompressible knitted adjunct;

FIG. 21A is a perspective view of another exemplary embodiment of acompressible knitted adjunct; and

FIG. 21B is a cross-sectional view of the adjunct of FIG. 21A taken atline 21B-21B.

DETAILED DESCRIPTION

Certain exemplary embodiments will now be described to provide anoverall understanding of the principles of the structure, function,manufacture, and use of the adjuncts, systems, and methods disclosedherein. One or more examples of these embodiments are illustrated in theaccompanying drawings. Those skilled in the art will understand that theadjuncts, systems, and methods specifically described herein andillustrated in the accompanying drawings are non-limiting exemplaryembodiments and that the scope of the present invention is definedsolely by the claims. The features illustrated or described inconnection with one exemplary embodiment may be combined with thefeatures of other embodiments. Such modifications and variations areintended to be included within the scope of the present invention.

Surgical stapling assemblies and methods for manufacturing and using thesame are provided. In general, a surgical stapling assembly can includea staple cartridge having staples disposed therein and a compressible,knitted adjunct configured to be releasably retained on the staplecartridge. As discussed herein, the various adjuncts provided can beconfigured to compensate for variations in tissue properties, such asvariations in tissue thickness, and/or to promote tissue ingrowth whenthe adjuncts are stapled to tissue. Further, the various adjuncts can bedesigned in such a way that inhibits the fraying and/or tearing thereofThis can improve the aesthetics and/or structural integrity of theadjunct.

An exemplary stapling assembly can include a variety of features tofacilitate application of a surgical staple, as described herein andillustrated in the drawings. However, a person skilled in the art willappreciate that the stapling assembly can include only some of thesefeatures and/or it can include a variety of other features known in theart. Any stapling assembly known in the art can be used. The staplingassemblies described herein are merely intended to represent certainexemplary embodiments. Moreover, while the adjuncts are described inconnection with surgical staple cartridge assemblies, the adjuncts canbe used in connection with staple reloads that are not cartridge basedor any type of surgical device.

FIG. 1 illustrates an exemplary surgical stapling and severing device100 suitable for use with an implantable adjunct. The illustratedsurgical stapling and severing device 100 includes a staple applyingassembly 106 or end effector having an anvil 102 that is pivotablycoupled to an elongate staple channel 104. As a result, the stapleapplying assembly 106 can move between an open position, as shown inFIG. 1, and a closed position in which the anvil 102 is positionedadjacent to the elongate staple channel 104 to engage tissuetherebetween. The staple applying assembly 106 can be attached at itsproximal end to an elongate shaft 108 forming an implement portion 110.When the staple applying assembly 106 is closed, or at leastsubstantially closed, (e.g., the anvil 102 moves from the open positionin FIG. 1 toward the elongate staple channel) the implement portion 110can present a sufficiently small cross-section suitable for insertingthe staple applying assembly 106 through a trocar. While the device 100is configured to staple and sever tissue, surgical devices configured tostaple but not sever tissue are also contemplated herein.

In various instances, the staple applying assembly 106 can bemanipulated by a handle 112 connected to the elongate shaft 108. Thehandle 112 can include user controls such as a rotation knob 114 thatrotates the elongate shaft 108 and the staple applying assembly 106about a longitudinal axis of the elongate shaft 108, and a closuretrigger 116 which can pivot relative to a pistol grip 118 to close thestaple applying assembly 106. A closure release button 120 can beoutwardly presented on the handle 112 when the closure trigger 116 isclamped such that the closure release button 120 can be depressed tounclamp the closure trigger 116 and open the staple applying assembly106, for example.

A firing trigger 122, which can pivot relative to the closure trigger116, can cause the staple applying assembly 106 to simultaneously severand staple tissue clamped therein. In various instances, multiple firingstrokes can be employed using the firing trigger 122 to reduce theamount of force required to be applied by the surgeon's hand per stroke.In certain embodiments, the handle 112 can include one or more rotatableindicator wheels such as, for example, rotatable indicator wheel 124which can indicate the firing progress. A manual firing release lever126 can allow the firing system to be retracted before full firingtravel has been completed, if desired, and, in addition, the firingrelease lever 126 can allow a surgeon, or other clinician, to retractthe firing system in the event that the firing system binds and/orfails.

Additional details on the surgical stapling and severing device 100 andother surgical stapling and severing devices suitable for use with thepresent disclosure are described, for example, in U.S. Pat. No.9,332,984 and in U.S. Patent Publication No. 2009/0090763, thedisclosures of which are incorporated herein by reference in theirentireties. Further, the surgical stapling and severing device need notinclude a handle, but instead can have a housing that is configured tocouple to a surgical robot, for example, as described in U.S. PatentPublication No. 2019/0059889, the disclosure of which is incorporatedherein by reference in its entirety.

As further shown in FIG. 1, a staple cartridge 200 can be utilized withthe device 100. In use, the staple cartridge 200 is placed within andcoupled to the elongate staple channel 104. While the staple cartridge200 can have a variety of configurations, in this illustratedembodiment, the staple cartridge 200, which is shown in more detail inFIGS. 2A-2B, has a proximal end 202 a and a distal end 202 b with alongitudinal axis L_(C) extending therebetween. As a result, when thestaple cartridge 200 is inserted into the elongate staple channel 104(FIG. 1), the longitudinal axis L_(C) aligns with the longitudinal axisL_(S) of the elongate shaft 108. Further, the staple cartridge 200includes a longitudinal slot 210 defined by two opposing slot edges 210a, 210 b and configured to receive at least a portion of a firing memberof a firing assembly, like firing assembly 400 in FIG. 4, as discussedfurther below. As shown, the longitudinal slot 202 extends from theproximal end 202 a toward the distal end 202 b of the staple cartridge200. It is also contemplated herein that in other embodiments, thelongitudinal slot 202 can be omitted.

The illustrated staple cartridge 200 includes staple cavities 212, 214defined therein and each staple cavity 212, 214 is configured toremovably house at least a portion of a staple (not shown). The number,shape, and position of the staple cavities can vary and can depend atleast on the size and shape of the staples to be removably disposedtherein. In this illustrated embodiment, the staple cavities arearranged in two sets of three longitudinal rows, with the first set ofstaple cavities 212 positioned on a first side of the longitudinal slot210 and the second set of staple cavities 214 positioned on a secondside of the longitudinal slot 210. On each side of the longitudinal slot210, and thus for each set of rows, a first longitudinal row of staplecavities 212 a, 214 a extends alongside the longitudinal slot 210, asecond row of staple cavities 212 b, 214 b extends alongside the firstrow of staple cavities 212 a, 214 b, and a third row of staple cavities212 c 214 c extends alongside the second row of staple cavities 212 b,214 b. For each set of rows, the first row of staple cavities 212 a, 214b, the second row of staple cavities 212 b, 214 b, and the third row ofstaple cavities 214 c, 214 c are parallel to one another and thelongitudinal slot 210. Further, as shown, for each set of rows, thesecond row of staple cavities 212 b, 214 b is staggered with respect tothe first and third rows of staple cavities 212 a, 212 c 214 a, 214 c.In other embodiments, the staple cavity rows in each set 212, 214 arenot parallel to one another and/or the longitudinal slot 210.

The staples releasably stored in the staple cavities 212, 214 can have avariety of configurations. An exemplary staple 300 that can bereleasably stored in each of the staple cavities 212, 214 is illustratedin FIG. 3 in its unfired (pre-deployed, unformed) configuration. Theillustrated staple 300 includes a crown (base) 302 and two staple legs304 extending from each end of the crown 302. In this embodiment, thecrown 302 extends in a linear direction and the staple legs 304 have thesame unformed height, whereas in other embodiments, the crown can be astep up crown, and/or the staple legs can have different unformedheights. Further, prior to the staples 300 being deployed, the crowns302 can be supported by staple drivers that are positioned within thestaple cartridge 200 and, concurrently, the staple legs 304 can be atleast partially contained within the staple cavities 212, 214. Further,the staple legs 304 can extend beyond a top surface, like top surface206, of the staple cartridge 200 when the staples 300 are in theirunfired positions. In certain instances, as shown in FIG. 3, the tips306 of the staple legs 304 can be pointed and sharp which can incise andpenetrate tissue.

In use, staples 300 can be deformed from an unfired position into afired position such that the staple legs 304 move through the staplecavities 212, 214, penetrate tissue positioned between the anvil 102 andthe staple cartridge 200, and contact the anvil 102. As the staple legs304 are deformed against the anvil 102, the staple legs 304 of eachstaple 300 can capture a portion of the tissue within each staple 300and apply a compressive force to the tissue. Further, the staple legs304 of each staple 300 can be deformed downwardly toward the crown 302of the staple 300 to form a staple entrapment area in which the tissuecan be captured therein. In various instances, the staple entrapmentarea can be defined between the inner surfaces of the deformed legs andthe inner surface of the crown of the staple. The size of the entrapmentarea for a staple can depend on several factors such as the length ofthe legs, the diameter of the legs, the width of the crown, and/or theextent in which the legs are deformed, for example.

In some embodiments, all of the staples disposed within the staplecartridge 200 can have the same unfired (pre-deployed, unformed)configuration. In other embodiments, the staples can include at leasttwo groups of staples each having a different unfired (pre-deployed,unformed) configuration, e.g., varying in height and/or shape, relativeto one another, etc. For example, the staple cartridge 200 can include afirst group of staples having a first height disposed within the firstrow of staple cavities 212 a, 214 a, a second group of staples having asecond height disposed within the second row of staple cavities 212 b,214 b, and a third group of staples having a third height disposedwithin the third row of staple cavities 212 c 214 c. In someembodiments, the first, second, and third heights can be different, inwhich the third height is greater than the first height and the secondheight. In other embodiments, the first and second heights are the same,but the third height is different and greater than the first height andthe second height. A person skilled in the art will appreciate thatother combinations of staples are contemplated herein.

Further, the staples can include one or more external coatings, e.g., asodium stearate lubricant and/or an antimicrobial agent(s). Theantimicrobial agent(s) can be applied to the staples as its own coatingor incorporated into another coating, such as a lubricant. Non-limitingexamples of suitable antimicrobial agents include5-Chloro-2-(2,4-dichlorophenoxy)phenol, chlorhexidine, silverformulations (e.g., nano-crystalline silver), lauric arginate ethylester (LAE), octenidine, polyhexamethylene biguanide (PHMB),taurolidine, lactic acid, citric acid, acetic acid, and their salts.

Referring back to FIGS. 2A-2B, the staple cartridge 200 extends from atop surface or deck surface 206 to a bottom surface 208. The top surface206 is configured as a tissue-facing surface and the bottom surface 208is configured as a channel-facing surface. As a result, when the staplecartridge 200 is inserted into the elongate staple channel 104, as shownin FIG. 1, the top surface 206 faces the anvil 102 and the bottomsurface 208 (obstructed) faces the elongate staple channel 104. Further,the top surface 206 has two outer-most terminal longitudinal edges 207a, 207 b that are positioned distal to the longitudinal slot 210 of thestaple cartridge 200.

In some embodiments, the top surface 206 can include surface featuresdefined therein. For example, the surface features can be recessedchannels defined within the top surface 206. As shown in more detail inFIG. 2C, a first recessed channel 216 surrounds each first staple cavity212 a, 214 a. Each first recessed channel 216 is defined by asubstantially triangular wall 216 a having a vertex pointing proximally,a vertex pointing distally, and a vertex pointing laterally outwardly.Further, each first recessed channel 216 includes a first floor 206 awhich is at a first height from the top surface 206. A second recessedchannel 218 surrounds each second staple cavity 212 b, 214 b. Eachsecond recessed channel 218 is defined by a wall 218 a which issubstantially diamond-shaped comprising a vertex pointing proximally, avertex pointing distally, a vertex pointing laterally inwardly, and avertex pointing laterally outwardly relative to the longitudinal axis.Further, each second recessed channel 218 includes a second floor 206 bwhich is a second height from the top surface 206. A third recessedchannel 220 surrounds each third staple cavity 212 c, 214 c. Each thirdrecessed channel 220 is defined by a substantially triangular wall 220 acomprising a vertex pointing proximally, a vertex pointing distally, anda vertex pointing laterally inwardly relative to the longitudinal axis.Further, each third recessed channel 220 includes a third floor 206 cwhich is a third height from the top surface 206. In some embodiments,the first height of the first recessed channels 216, the second heightof the second recessed channels 218, and the third height of the thirdrecessed channels 220 can have the same height. In other instances, thefirst height, the second height, and/or the third height can bedifferent. Additional details on the surface features and otherexemplary surface features can be found in U.S. Publication No.2016/0106427, which is incorporated by reference herein in its entirety.

With reference to FIGS. 4 and 5, a firing assembly such as, for example,firing assembly 400, can be utilized with a surgical stapling andsevering device, like device 100 in FIG. 1. The firing assembly 400 canbe configured to advance a wedge sled 500 having wedges 502 configuredto deploy staples from the staple cartridge 200 into tissue capturedbetween an anvil, like anvil 102 in FIG. 1, and a staple cartridge, likestaple cartridge 200 in FIG. 1. Furthermore, an E-beam 402 at a distalportion of the firing assembly 400 may fire the staples from the staplecartridge. During firing, the E-beam 402 can also cause the anvil topivot towards the staple cartridge, and thus move the staple applyingassembly from the open position towards a closed position. Theillustrated E-beam 402 includes a pair of top pins 404, a pair of middlepins 406, which may follow a portion 504 of the wedge sled 500, and abottom pin or foot 408. The E-beam 402 can also include a sharp cuttingedge 410 configured to sever the captured tissue as the firing assembly400 is advanced distally, and thus towards the distal end of the staplecartridge. In addition, integrally formed and proximally projecting topguide 412 and middle guide 414 bracketing each vertical end of the sharpcutting edge 410 may further define a tissue staging area 416 assistingin guiding tissue to the sharp cutting edge 410 prior to being severed.The middle guide 414 may also serve to engage and fire the stapleswithin the staple cartridge by abutting a stepped central member 506 ofthe wedge sled 500 that effects staple formation by the staple applyingassembly 106.

In use, the anvil 102 in FIG. 1 can be moved into a closed position bydepressing the closure trigger in FIG. 1 to advance the E-beam 402 inFIG. 4. The anvil can position tissue against at least the top surface206 of the staple cartridge 200 in FIGS. 2A-2C. Once the anvil has beensuitably positioned, the staples 300 in FIG. 3 disposed within thestaple cartridge can be deployed.

To deploy staples from the staple cartridge, as discussed above, thewedge sled 500 in FIG. 5 can be moved from the proximal end toward adistal end of the cartridge body, and thus, of the staple cartridge. Asthe firing assembly 400 in FIG. 4 is advanced, the sled can contact andlift staple drivers within the staple cartridge upwardly within thestaple cavities 212, 214. In at least one example, the sled and thestaple drivers can each include one or more ramps, or inclined surfaces,which can co-operate to move the staple drivers upwardly from theirunfired positions. As the staple drivers are lifted upwardly withintheir respective staple cavities, the staples are advanced upwardly suchthat the staples emerge from their staple cavities and penetrate intotissue. In various instances, the sled can move several staples upwardlyat the same time as part of a firing sequence.

As indicated above, the stapling device can be used in combination witha compressible adjunct. A person skilled in the art will appreciatethat, while adjuncts are shown and described below, the adjunctsdisclosed herein can be used with other surgical devices, and need notbe coupled to a staple cartridge as described. Further, a person skilledin the art will also appreciate that the staple cartridges need not bereplaceable.

As discussed above, with some surgical staplers, a surgeon is oftenrequired to select the appropriate staples having the appropriate stapleheight for tissue to be stapled. For example, a surgeon will utilizetall staples for use with thick tissue and short staples for use withthin tissue. In some instances, however, the tissue being stapled doesnot have a consistent thickness and thus, the staples cannot achieve thedesired fired configuration for every section of the stapled tissue(e.g., thick and thin tissue sections). The inconsistent thickness oftissue can lead to undesirable leakage and/or tearing of tissue at thestaple site when staples with the same or substantially greater heightare used, particularly when the staple site is exposed tointra-pressures at the staple site and/or along the staple line.

Accordingly, various embodiments of knitted adjuncts are provided thatcan be configured to compensate for varying thickness of tissue that iscaptured within fired (deployed) staples to avoid the need to take intoaccount staple height when stapling tissue during surgery. That is, theadjuncts described herein can allow a set of staples with the same orsimilar heights to be used in stapling tissue of varying thickness(e.g., from thin to thick tissue) while also, in combination with theadjunct, providing adequate tissue compression within and between firedstaples. Thus, the adjuncts described herein can maintain suitablecompression against thin or thick tissue stapled thereto to therebyminimize leakage and/or tearing of tissue at the staple sites.

Alternatively or in addition, the knitted adjuncts can be configured topromote tissue ingrowth. In various instances, it is desirable topromote the ingrowth of tissue into an implantable adjunct, to promotethe healing of the treated tissue (e.g., stapled and/or incised tissue),and/or to accelerate the patient's recovery. More specifically, theingrowth of tissue into an implantable adjunct may reduce the incidence,extent, and/or duration of inflammation at the surgical site. Tissueingrowth into and/or around the implantable adjunct may, for example,manage the spread of infections at the surgical site. The ingrowth ofblood vessels, especially white blood cells, for example, into and/oraround the implantable adjunct may fight infections in and/or around theimplantable adjunct and the adjacent tissue. Tissue ingrowth may alsoencourage the acceptance of foreign matter (e.g., the implantableadjunct and the staples) by the patient's body and may reduce thelikelihood of the patient's body rejecting the foreign matter. Rejectionof foreign matter may cause infection and/or inflammation at thesurgical site.

In general, the knitted adjuncts provided herein are designed andpositioned atop a staple cartridge, like staple cartridge 200. When thestaples are fired (deployed) from the cartridge, the staples penetratethrough the adjunct and into tissue. As the legs of the staple aredeformed against the anvil that is positioned opposite the staplecartridge, the deformed legs capture a portion of the adjunct and aportion of the tissue within each staple. That is, when the staples arefired into tissue, at least a portion of the adjunct becomes positionedbetween the tissue and the fired staple. While the adjuncts describedherein can be configured to be attached to a staple cartridge, it isalso contemplated herein that the adjuncts can be configured to matewith other device components, such as an anvil of a surgical stapler. Aperson of ordinary skill will appreciate that the adjuncts providedherein can be used with replaceable cartridges or staple reloads thatare not cartridge based.

FIG. 6 illustrates an exemplary embodiment of a stapling assembly 600that includes a staple cartridge 602 and an adjunct 604. For sake ofsimplicity, the adjunct 604 is generally illustrated in FIGS. 6A-6B, andvarious structural configurations of the adjunct are described in moredetail below. Aside from the differences described in detail below, thestaple cartridge 602 can be similar to staple cartridge 200 (FIGS. 1-3)and therefore common features are not described in detail herein. Asshown, the adjunct 604 is positioned against the staple cartridge 602.While partially obstructed in FIG. 6, the staple cartridge 602 includesstaples 606, which can be similar to staple 300 in FIG. 3, that areconfigured to be deployed into tissue. The staples 606 can have anysuitable unformed (pre-deployed) height. For example, the staples 606can have an unformed height between about 2 mm and 4.8 mm. Prior todeployment, the crowns of the staples can be supported by staple drivers(not shown).

In the illustrated embodiment, the adjunct 604 can be mated to at leasta portion of the top surface or deck surface 608 of the staple cartridge602. In some embodiments, the top surface 608 of the staple cartridge602 can include one or more surface features, like recessed channels216, 218, 220 as shown in FIGS. 2A and 2C. The one or more surfacefeatures can be configured to engage the adjunct 604 to avoidundesirable movements of the adjunct 604 relative to the staplecartridge 602 and/or to prevent premature release of the adjunct 604from the staple cartridge 602. Exemplary surface features are describedin U.S. Patent Publication No. 2016/0106427, which is incorporated byreference herein in its entirety.

The adjunct 604 is compressible to permit the adjunct to compress tovarying heights to thereby compensate for different tissue thicknessthat are captured within a deployed staple. The adjunct 604 has anuncompressed (undeformed), or pre-deployed, height and is configured todeform to one of a plurality of compressed (deformed), or deployed,heights. For example, the adjunct 604 can have an uncompressed heightwhich is greater than the fired height of the staples 606 disposedwithin the staple cartridge 602 (e.g., the height (H) of the firedstaple 606 a in FIG. 7). That is, the adjunct 604 can have an undeformedstate in which a maximum height of the adjunct 604 is greater than amaximum height of a fired staple (e.g., a staple that is in a formedconfiguration). In one embodiment, the uncompressed height of theadjunct 604 can be about 10% taller, about 20% taller, about 30% taller,about 40% taller, about 50% taller, about 60% taller, about 70% taller,about 80% taller, about 90% taller, or about 100% taller than the firedheight of the staples 606. In certain embodiments, the uncompressedheight of the adjunct 604 can be over 100% taller than the fired heightof the staples 606, for example.

In use, once the surgical stapling and severing device, like device 100in FIG. 1, is directed to the surgical site, tissue is positionedbetween the anvil 612 and the stapling assembly 600 such that the anvil612 is positioned adjacent to a first side of the tissue and thestapling assembly 600 is positioned adjacent to a second side of thetissue (e.g., the tissue can be positioned against the tissue-contactingsurface 604 a of the adjunct 604). Once tissue is positioned between theanvil 612 and the stapling assembly 600, the surgical stapler can beactuated, e.g., as discussed above, to thereby clamp the tissue betweenthe anvil 612 and the stapling assembly 600 (e.g., between thetissue-compression surface 612 a of the anvil 612 and thetissue-contacting surface 604 a of the adjunct 604) and to deploystaples from the cartridge through the adjunct and into the tissue tostaple and attach the adjunct to the tissue.

As shown in FIG. 7, when the staples 606 are fired, tissue (T) and aportion of the adjunct 604 are captured by the fired (formed) staples606 a. The fired staples 606 a each define the entrapment area therein,as discussed above, for accommodating the captured adjunct 604 andtissue (T). The entrapment area defined by a fired staple 606 a islimited, at least in part, by a height (H) of the fired staple 606 a.For example, the height of a fired staple 606 a can be about 0.160inches or less. In some embodiments, the height of a fired staple 606 acan be about 0.130 inches or less. In one embodiment, the height of afired staple 606 a can be from about 0.020 inches to 0.130 inches. Inanother embodiment, the height of a fired staple 606 a can be from about0.060 inches to 0.160 inches.

As described above, the adjunct 604 can be compressed within a pluralityof fired staples whether the thickness of the tissue captured within thestaples is the same or different within each fired staple. In at leastone exemplary embodiment, the staples within a staple line, or row canbe deformed such that the fired height is about 2.75 mm, for example,where the tissue (T) and the adjunct 604 can be compressed within thisheight. In certain instances, the tissue (T) can have a compressedheight of about 1.0 mm and the adjunct 604 can have a compressed heightof about 1.75 mm. In certain instances, the tissue (T) can have acompressed height of about 1.50 mm and the adjunct 604 can have acompressed height of about 1.25 mm. In certain instances, the tissue (T)can have a compressed height of about 1.75 mm and the adjunct 604 canhave a compressed height of about 1.00 mm. In certain instances, thetissue (T) can have a compressed height of about 2.00 mm and the adjunct604 can have a compressed height of about 0.75 mm. In certain instances,the tissue (T) can have a compressed height of about 2.25 mm and theadjunct 604 can have a compressed height of about 0.50 mm. Accordingly,the sum of the compressed heights of the captured tissue (T) and adjunct604 can be equal, or at least substantially equal, to the height (H) ofthe fired staple 606 a.

The knitted adjuncts can have a variety of configurations. In general,and as described in more detail below, the knitted adjuncts are formedof fibers that are knitted or woven (e.g., intertwined) together.

The knitted adjuncts can be formed of the same fibers, whereas in otherembodiments, the knitted adjuncts can be formed of different fibers. Thefibers can differ by material, dimensions (e.g., height and/ordiameter), and/or structural configuration (e.g., monofilament ormultifilament). In certain embodiments, the knitted adjuncts can includemonofilament and/or multifilament fibers. As used herein, the term“monofilament fibers” has its own ordinary and customary meaning and caninclude fibers formed of a single filament. As used herein, the term“multifilament fibers” has its own ordinary and customary meaning andcan include fibers formed of two or more filaments that are associatedwith one another (e.g., twisted or braided) to form a unitary structure.

The multifilament fibers can have a variety of configurations. Forexample, in some embodiments, each multifilament fiber includes fromabout 6 to 40 filaments. In one embodiment, each multifilament fiberincludes from about 14 to 28 filaments. The increased surface area andvoids that exist between the filaments of the multifilament fibers canfacilitate improved tissue ingrowth within the adjunct.

The multifilament fibers can be formed of filaments formed of the samematerial or filaments of different materials. For example, in someembodiments, the multifilament fibers can include first filaments of afirst material and second filaments of a second material. In oneembodiment, the second material degrades at a faster rate than adegradation rate of the first material. In this way, the degradation ofthe second material can activate, and thus encourage acceleratedattraction of, macrophages and accelerate the inflammation phase ofhealing while not substantially affecting the variable stiffness profileof the adjunct over time following implantation. The activation ofmacrophages can in turn cause increases in myofibroblast population andneovascularization. Further, the degradation of the second material canencourage tissue ingrowth within the adjunct. The first material, forexample, can be at least one of poly-L-lactic acid, a copolymer ofglycolide and L-lactide, a copolymer of glycolic acid and lactic acid,poly(lactic-co-glycolic acid), poly(lactic acid), polyglycolide, and acopolymer of glycolide, caprolactone, trimethylene carbonate, andlactide. Non-limiting examples of suitable first materials can be formedof polyglactin 910, Lactomer™ 9-1, 75:25 or 50:50 lactic acid/glycolicacid, Polygytone™ 6211, or Caprosyn™. The second material, for example,can be a copolymer of glycolide and L-lactide, such as Vicryl Rapide™.

While the multifilament fibers can include the second filaments atvarious percentage ranges, in some embodiments, the multifilament fiberscan each include second filaments at a range of about 15% to 85% or at arange of about 25% to 45%. The second filaments can have various fiberdiameters. For example, in some embodiments, the second filaments canhave a fiber diameter from about 0.0005 mm to 0.02 mm. In oneembodiment, the second filaments have a fiber diameter of about 0.015mm.

The monofilament fibers can have a variety of sizes. For example, themonofilaments can have a diameter of about 0.2 mm to 0.35 mm. In someembodiments, the monofilament fibers can each have a diameter that isless than an average fiber diameter of the multifilament fibers. Theaverage fiber diameter (D) of a multifilament fiber can be calculatedusing the following formula:

$D = \sqrt{\frac{4W}{N\;{\rho\pi}}}$

wherein:

-   -   W=weight of multifilament fiber (fiber bundle) per unit length    -   N=number of filaments    -   p=density of fiber.

The multifilament fibers can have a variety of sizes. For example, eachmultifilament fiber can have an average fiber diameter of about 0.02 mmto 0.2 mm, of about 0.05 mm to 0.2 mm, or of about 0.15 mm to 0.2 mm. Insome embodiments, each filament of the multifilament fibers has adiameter that is less than a fiber diameter of the monofilament fibers.For example, where the adjunct includes first fibers that aremultifilament fibers and second fibers that are monofilament fibers,each filament of the multifilament fibers can have a diameter that isabout ⅕ to 1/20 the diameter of the monofilament fibers. In certainembodiments, each filament of the multifilament fibers can have adiameter that is about 1/10 the diameter of the monofilament fibers.

As discussed above, a portion of the adjunct is captured with tissuewithin the fired staple and therefore it is desirable that the adjunctbe formed of suitable bioabsorbable materials. As such, the fibers caneach be formed of bioabsorbable material(s). Non-limiting examples ofsuitable bioabsorbable materials include poly-L-lactic acid, a copolymerof glycolide and L-lactide, a copolymer of glycolic acid and lacticacid, poly(lactic-co-glycolic acid), poly(lactic acid), polyglycolide,and a copolymer of glycolide, caprolactone, trimethylene carbonate, andlactide, polydioxanone, a copolymer of polydioxanone and polyglycolide,a copolymer of lactide and polycaprolactone), a copolymer of glycolide,dioxanone, and trimethylene carbonate, poly(trimethylene carbonate),polyhydroxyalkanoate, and polyglyconate.

In some embodiments, a knitted adjunct can include at least twodifferent types of fibers. Non-limiting examples of suitable materialsfor the first type of fibers include at least one of poly-L-lactic acid,a copolymer of glycolide and L-lactide, a copolymer of glycolic acid andlactic acid, poly(lactic-co-glycolic acid), poly(lactic acid),polyglycolide, and a copolymer of glycolide, caprolactone, trimethylenecarbonate, and lactide. For example, the first type of fibers can beformed of polyglactin 910, Lactomer™ 9-1, 75:25 or 50:50 lacticacid/glycolic acid, Polygytone™ 6211, or Caprosyn™. Non-limitingexamples of suitable materials for the second type of fibers include atleast one of polydioxanone, a copolymer of polydioxanone andpolyglycolide, a copolymer of lactide and polycaprolactone), a copolymerof glycolide, dioxanone, and trimethylene carbonate, poly(trimethylenecarbonate), polyhydroxyalkanoate, and polyglyconate. For example, thesecond type of fibers can be formed of 92:8 polydioxanone/Polyglycolide,25:75 lactide/polycaprolactone, Glycomer™ 631, or Maxon™. In oneembodiment, the first type of fibers is formed of polyglactin 910 andthe second type of fibers is formed of polydioxanone.

The knitted adjuncts can have various sizes, shapes, and configurations.In general, an adjunct includes at least core or intermediate layer andat least one outer layer. For example, the adjunct can include a firstouter layer (e.g. a top or tissue-contacting layer) formed of at leastfirst fibers that are knitted or woven together (e.g., a knitted layer)and a second outer layer (e.g., a bottom or cartridge-contacting layer)formed of at least second fibers that are knitted or woven together(e.g., a knitted layer). The first and second fibers can be the same ordifferent. The adjunct can also include spacer fibers that can be thesame or different than the first and second fibers. The spacer fibersintertwine with and extend between the first and second outer layers tothereby connect these layers together such that the portions of thespacer fibers extending between the two outer layers form at least oneof the at least one core or intermediate layer of the adjunct.

Each layer of the adjunct extends from a first surface (e.g., a topsurface) to a second surface (e.g., a bottom surface). Depending on theoverall structural configuration of the adjunct, at least a portion ofthe first surface of one layer can serve as a tissue-contacting surface,and at least a portion of the second surface of another layer can serveas a cartridge-contacting surface. A person skilled in the art willappreciate that the adjunct can have additional tissue-contactingsurfaces (e.g., one or more lateral side surfaces relative to the topsurface).

In some embodiments, the spacer fibers interconnect with the first andsecond fibers of the outer layers in a manner in which the spacersfibers are non-fixedly attached and slidably interconnected. As such,the fibers can move relative to each other, thereby allowing formovement and for expansion of the knitted adjunct in the x-direction(e.g., stretch) and the y-direction (e.g., compression). Additionally,the interconnection between the spacer fibers and the first and secondfibers of the outer layers can affect, at least in part, the stiffnessof the adjunct. For example, the tighter the interconnections, thestiffer the adjunct.

The first and second outer layers can each include a plurality ofopenings formed therein. The perimeter of the openings of the firstouter layer can be defined by portions of the first fibers and of thespacer fibers, whereas the perimeter of the openings of the second outerlayer can be defined by portions of the second fibers and of the spacerfibers. In certain embodiments, the openings of the second outer layercan have a size that is less than about ¹/₄ of a width of a crown of astaple, like staple 300 in FIG. 3. In such embodiments, the crown of thefired staple can therefore span over at least four openings in thesecond outer layer. In one embodiment, the openings can have a size thatis about ⅛ of the width of the crown. While the crown of a staple canhave a variety of widths, in some embodiments, the width of the crowncan be about 0.080 inches to 0.140 inches. In one embodiment, the widthof the crown is about 0.12 inches.

In certain embodiments, the portions of the spacer fibers that extendbetween the first and second outer layers can be arranged to formstanding fibers and a plurality of voids therebetween. The standingfibers are non-fixedly attached to each other. Further, the standingfibers are non-fixedly and slidably interconnected to the first type offibers of the first and second outer layers. In some implementations,the plurality of voids can be larger than the plurality of openings inthe first and second outer layers.

The standing fibers can be configured to bend under force being appliedto the adjunct (e.g., when stapled to tissue). The resilience of thestanding fibers permits the adjunct, at least in part, to compress atvarious heights to thereby accommodate tissue (T) with tissue portionsof different thicknesses. That is, independent of the particular tissuethickness, the sum of the compressed heights of the captured tissue andadjunct within the fired staple can be maintained, and thus can remainequal, or at least substantially equal, to the height of the firedstaple. In this way, at least in part, the knitted adjunct can beconfigured to apply a stress of at least about 3 gf/mm² to the capturedtissue for at least a predetermined period (e.g., at least about 3days).

Generally, the material composition, the height, and/or the transversecross-sectional area of each standing fiber controls, at least in part,its stiffness or ability to bend under compression which, in turn,controls, at least in part, the overall compressibility of the adjunct.Accordingly, the standing fibers can be configured to tune thecompressibility of the adjunct to one or more desired values. Forexample, in some embodiments, the standing fibers can be formed of thesame material, whereas in other embodiments, at least a portion of thestanding fibers can be formed of different materials with differentstiffnesses. Alternatively or in addition, the standing fibers, or atleast a portion thereof, can have different heights and/or transversecross-sectional areas.

The amount of the standing fibers within a certain region or section ofthe adjunct can also affect, among other things, the compressibility ofsuch section, and thus the overall compressibility of the adjunct. Incertain instances, the standing fibers can be strategically concentratedin certain regions of adjunct to provide greater compression strength insuch regions, for example. In at least one instance, the standing fiberscan be concentrated in regions of the core or intermediate layer thatare configured to receive staples when the staples are fired.Alternatively, the standing fibers can be concentrated in regions of theadjunct that do not receive staples when the staples are fired (e.g.,regions that overlap with the intended cut-line of the adjunct).

The ratio of the voids to the standing fibers can vary. In someembodiments, this ratio can be in the range of at least about 3:1. Inother embodiments, the ratio of voids to the standing fibers can in therange of at least about 5:1 or of at least about 12:1. Further, at leasta portion of the voids can each have a different size. In this way, thevariable void sizes throughout the cross-section of the adjunct 804 canpromote extracellular remodeling. That is, the variable void sizes canfacilitate revascularization as well as mobility of cells within theadjunct when the adjunct is implanted, thereby encouraging both tissueand cellular ingrowth. Further the variable void sizes can alsofacilitate extraction of byproducts and cellular waste from theimplanted adjunct, and thus the implantation site.

Edges Conditions

As discussed above, the knitted adjuncts are formed of fibers that areknitted or woven together. In certain embodiments, the knitted adjunctscan be designed such that the free ends of at least a portion of thefibers are connected together so as to form one or more finished edgesof the adjunct. The one or more finished edges are configured tosubstantially, or completely, prevent fraying or fiber separationtherealong. As a result, the structural integrity of the adjunct can bemaintained when exposed to forces that would otherwise cause the fibersto fray or separate from each other. The one or more finished edges canalso provide an aesthetic effect and/or decrease the variability in boththe structure and attendant properties of the present adjuncts, ascompared to conventional adjuncts (e.g., adjuncts that do not havefinished edges).

The one or more finished edges can be formed in a variety of ways. Forexample, in some embodiments, additional fiber(s) (e.g., fibersdifferent than those used to form the main body of the adjunct) can beused to interconnect the terminal edges of opposing layers of theadjunct together (see FIGS. 8A-10D). In such embodiments, the additionalfiber(s) can be knitted or woven into the terminal edges in a variety ofconfigurations (e.g., as an overcast stitch, an overedge stitch, azizzag stitch, and the like).

FIGS. 8A-8B illustrate one exemplary embodiment of a stapling assembly800 that includes a staple cartridge 802 and a knitted adjunct 804disposed on a top or deck surface 803 of the staple cartridge 802. Thestaple cartridge 802 is similar to staple cartridge 200 in FIGS. 1-2C,and therefore common features are not described in detail herein.

In this illustrated embodiment, as shown in more detail in FIG. 8B, theadjunct 804 includes a top layer 806 (e.g., a tissue-contacting layer)formed of at least first fibers 808, a bottom layer 810 (e.g., acartridge-contacting layer) formed of at least second fibers 812, andspacer fibers 814 that are intertwined with and extending between thetop and bottom layers 806, 810 to thereby connect the top and bottomlayers 806, 810 together. In this illustrated embodiment, the spacerfibers 814 are multi-looped about the first fibers 808 and about secondfibers 812. The portions of the spacer fibers 814 that extend betweenthe top and bottom layers 806, 810 form an intermediate or core layer816 of the adjunct 804. For sake of simplicity, only one first fiber808, second fiber 812, and spacer fiber 814 is illustrated in FIG. 8B. Aperson skilled in the art will appreciate that the following discussionis also applicable to the remaining first, second, and spacer fibers ofthe adjunct.

The top and bottom layers 806, 810 can have a variety of structuralconfigurations. As shown, the top layer 806 has two outer-mostlongitudinal terminal edges 806 a, 806 b, and the bottom layer has twoouter-most longitudinal terminal edges 810 a, 810 b. In someembodiments, the first fibers 808 of the top layer 806 can be knitted orwoven into a first predetermined pattern and/or the second fibers 812 ofthe bottom layer 810 can be knitted or woven into a second predeterminedpattern. In certain embodiments, the first and second predeterminedpatterns can be generally identical (e.g., nominally identical withinmanufacturing tolerances), whereas in other embodiments, the first andsecond predetermined patterns can be different. While the first fibers808 and the second fibers 812 can be knitted or woven in variouspatterns, in certain embodiments, the first fibers 808 can be knittedinto a first Raschel knit pattern and the second fibers 812 can beknitted into a second Raschel knit pattern that is the same or differentthan the first Raschel knit pattern. Further, in some embodiments, thefiber density of the top layer 806 can be different than the fiberdensity of the bottom layer 810. A person skilled in the art willappreciate that the first fibers 808 and the second fibers 812 can berandomly or repeatedly knitted or woven within the top and bottom layers806, 810, respectively. As such, and for sake of simplicity, the top andbottom layers 806, 810 are generally illustrated, and thus the specificstructural configurations of the top and bottom layers 806, 810 are notlimited to what is depicted in the figures.

The first fibers 808, the second fibers 812, and the spacer fibers 814can have a variety of configurations. For example, in some embodiments,the first fibers 808, the second fibers 812, and the spacer fibers 814can be generally identical (e.g., nominally identical withinmanufacturing tolerances) in material and/or structural configuration.In other embodiments, the first and second fibers 808, 812 can begenerally identical (e.g., nominally identical within manufacturingtolerances) in material and/or structural configuration relative to eachother and the spacer fibers 814 can be different relative thereto. Forexample, in certain embodiments, the first and second fibers 808, 812can be multifilament fibers, and the spacer fibers 814 can bemonofilament fibers. As such, aside from the general overall shape, thespecific structural configuration of each of the first fibers 808, thesecond fibers 812, and the spacer fibers 814 is not shown.

While the adjunct 804 can have a variety of configurations, in theembodiment shown in FIG. 8B, the adjunct 804 includes an inner-mostsegment 820 that includes the first fibers 808, the second fibers 812,and the spacer fibers 814, and first and second outer-most segments 822,824 that are positioned on opposite sides (e.g., longitudinal sides) ofthe inner-most segment 820 and along the longitudinal axis LA of theadjunct (e.g., in the z-direction). As a result, when the adjunct 804 isreleasably coupled to the top or deck surface 803 of the staplecartridge 802, the first outer-most segment 822 is adjacent to andextends along the first outer-most longitudinal edge 805 a of the topsurface 803 and the second outer-most segment 824 is adjacent to andextends along the second outer-most longitudinal edge 805 b of the topsurface 803 of the cartridge 802.

While the first and second outer-most segments 822, 824 can havedifferent structural configurations, in this illustrated embodiment, thefirst and second outer-most segments 822, 824 are generally identical(e.g., nominally identical within manufacturing tolerances). The firstand second outer-most segments 822, 824 each include only the firstfibers 808 and the second fibers 812, and thus only portions of the topand bottom layers 806, 810. That is, in this illustrated embodiment, thespacer fibers 814 are not present within the first and second outer-mostsegments 822, 824, and as a result, the mechanical behavior of theadjunct 804 can be predominately controlled by the inner-most segment820, and consequently, by the mechanical behavior of the spacer fibers814. In other embodiments, the first outer-most segment 822 and/or thesecond outer-most segment 824 can include the spacer fibers 814.Further, as shown, the first outer-most segment 822 includes the firstouter-most longitudinal terminal edges 806 a, 810 a of the top andbottom layers 806, 810, each of which includes a portion of the freeends of the first fibers 808 and of the second fibers 812. Similarly,the second outer-most segment 824 includes the second outer-mostlongitudinal terminal edges 806 b, 810 b of the top and bottom layers806, 810, each of which includes a portion of the free ends of the firstfibers 808 and of the second fibers 812.

As shown in more detail in FIG. 8B, the portions of the top and bottomlayers 806, 810 within the inner-most segment 820 extend parallel to oneanother along the longitudinal axis L_(A) (e.g., extending in thez-direction) of the adjunct 804 and are spaced apart at a distance D.Similarly, the respective portions of the top layer 806 and bottom layer810 within the first and second outer-most segments 822, 824 extendparallel to one another along the longitudinal axis L_(A) of the adjunct804 (e.g., extending in the z-direction) and are spaced apart at arespective distance D₁, D₂. As such, the portions of the top and bottomlayers 806, 810 within the first outer-most segment 822 at leastpartially overlap with each other and the portions of the top and bottomlayers 806, 810 within the second outer-most segment 824 at leastpartially overlap with each other. While in certain embodiments thedistances D, D₁, D₂ can be all the same or all different, in thisillustrated embodiment, distance D is different than distance D₁ anddistance D₂, with distance D₁ and distance D₂ being generally identical(nominally identical within manufacturing tolerances).

The difference between distance D and distances D₁, D₂ is due to thetapering transition between the inner-most segment 820 and the first andsecond outer-most segments 822, 824 of the adjunct 804 via first andsecond intermediate segments 826, 828. The first intermediate segment826 extends from the inner-most segment 820 to the first outer-mostsegment 822 and the second intermediate segment 828 extends from theinner-most segment 820 to the second outer-most segment 824. The firstand second intermediate segments 826, 828 are tapered in whichrespective portions of the top layer 806 extend at an angle relative torespective portions of the bottom layer 810. As shown, the respectiveportions of the top layer 806 extend towards respective portions of thebottom layer 810 within the first and second intermediate segments 826,828. As a result, the distance D between the portion of the top andbottom layers 806, 810 of the inner-most segment 820 is greater than thedistances D₁, D₂ between the portion of the top and bottom layers 806,810 of the first outer-most segment and of the second outer-mostsegment, respectively. This relationship between distance D anddistances D₁, D₂ can allow additional fiber(s), like first and secondadditional fibers 830, 832, to be used to interconnect the one or moreterminal edges of the top and bottom layers 806, 810 without adverselyaffecting the overall mechanical behavior of the adjunct 804.

As further shown, the adjunct 804 includes first additional fiber 830(FIG. 8B) and second additional fiber 832 (FIGS. 8A-8B). The first andsecond additional fibers 830, 832 form respective first and secondfinished edges 834, 836, in which each finished edge is configured toprevent fraying of the top and bottom layers 806, 810 therealong, andthus fraying and/or fiber separation of the first fibers 808 and thesecond fibers 812.

The first and second additional fibers 830, 832 can have a variety ofconfigurations. In some embodiments, the first additional fiber 830 andthe second additional fiber 832 can be generally identical (nominallyidentical within manufacturing tolerances) in compositional makeup(e.g., formed of the same material(s)), dimension(s) (e.g., heightand/or diameter) and/or in structural configuration (e.g., monofilamentor multifilament). In certain embodiments, the first additional fiber830 and/or the second additional fiber 832 can be a monofilament fiber.In other embodiments, the first additional fiber 830 and/or the secondadditional fiber 832 can be a multifilament fiber. As such, aside fromthe general overall shape, the specific structural configuration of thefirst and second additional fibers 830, 832 is not shown. Further, whileonly one first additional fiber and one second additional fiber areillustrated in FIGS. 8A-8B, a person skilled in the art will appreciatethat more than one first additional fiber and/or more than one secondadditional fiber and/or other additional fiber(s) can be used to formthe finished edges of the adjunct.

The first and second additional fibers 830, 832 can be incorporated intothe adjunct 804 in a variety of ways to form the first and secondfinished edges 834, 836. In this illustrated embodiment, the firstadditional fiber 830 interconnects the top and bottom layers 806, 810along their first outer-most longitudinal terminal edges 806 a, 810 a toform the first finished edge 834. As a result, the first finished edge834 is formed of the first fibers 808, the second fibers 812, and thefirst additional fiber 830 and is positioned along, and thus defines, atleast a portion of a first outer-most longitudinal edge 838 of theadjunct 804. The second additional fiber 832 interconnects the top andbottom layers 806, 810 along their respective second outer-mostlongitudinal terminal edges 806 b, 810 b to form the second finishededge 836. As a result, the second finished edge 836 is formed of thefirst fibers 808, the second fibers 812, and the second additional fiber832 and is positioned along, and thus defines, at least a portion of asecond outer-most longitudinal edge 840 of the adjunct 804. Thus, atleast a portion of the outer-most perimeter of the adjunct is defined bythe first and second finished edges 834, 836.

Further, the first additional fiber 830 and/or the second additionalfiber 832 can be configured as an overcast stitch. For example, as shownin greater detail in FIG. 8B, the first additional fiber 830 and thesecond additional fiber 832 are wrapped around the first outer-mostlongitudinal terminal edges 806 a, 810 a and the second outer-mostlongitudinal terminal edges 806 b, 810 b, respectively, in the form ofloops (e.g., in a spiral-type or zig-zag configuration). As a result,the portion of free ends of the first and second fibers 808, 812 at thefirst outer-most longitudinal terminal edges 806 a, 810 a are securedtogether by the first additional fiber 830 and the portion of free endsof the first and second fibers 808, 812 at the second outer-mostlongitudinal terminal edges 806 b, 810 b are secured together by thesecond additional fiber 832. In other embodiments, the first and secondadditional fibers 830, 832 can be configured as other suitable stitchforms. Further, in certain embodiments, the first and second additionalfibers 830, 832 can configured as different stitch forms.

FIGS. 9A-9B illustrate another exemplary embodiment of a knitted adjunct900 having one or more finished edges formed by respective additionalfibers. Aside from the differences discussed below, the adjunct 900 issimilar to adjunct 804 in FIGS. 8A-8B, and therefore common features arenot described in detail herein.

The adjunct 900 includes a top layer 906 (e.g., a tissue-contactinglayer) formed of first fibers 908, a bottom layer 910 (e.g., acartridge-contacting layer) formed of second fibers 912, and spacerfibers 914 that are intertwined with and that extend between the top andbottom layers 906, 910 to thereby connect the top and bottom layers 906,910 together. As shown in FIG. 9A, the top layer 906 has at least twoouter-most longitudinal terminal edges 906 a, 906 b and at least twoouter-most lateral terminal edges 906 c, 906 d. The bottom layer 910 hasat least two outer-most longitudinal terminal edges (only one outer-mostlongitudinal terminal edge 910 b being illustrated in FIG. 9A) and atleast two outer-most lateral terminal edges 910 c, 910 d.

In addition to the first and second outer-most segments 915, 916 (seeFIG. 9A), which are similar to the first and second outer-most segments822, 824 in FIGS. 8A-8B, the adjunct 900 includes third and fourthouter-most segments 918, 920 (see FIG. 9B). The third and fourthouter-most segment 918, 920 are positioned on opposite sides (e.g.,lateral sides) of the inner-most segment 922 and extend orthogonal(e.g., in the y-direction) to the longitudinal axis L_(A) of the adjunct(e.g., extending the z-direction). Aside from their position within theadjunct 900, the third and fourth outer-most segments 918, 920 arestructurally similar to the first and second outer-most segments 915,916.

Further, in addition to the first and second intermediate segments 924,926 (see FIG. 9A), which are similar to the first and secondintermediate segments 826, 828 in FIGS. 8A-8B, the adjunct 900 includesthird and fourth intermediate segments 928, 930 (see FIG. 9B). As shown,the third intermediate segment 928 extends from the inner-most segment922 to the third outer-most segment 918 and the fourth intermediatesegment 930 extends from the inner-most segment 922 to the fourthouter-most segment 920. Aside from their position within the adjunct900, the third and fourth intermediate segments 928, 930 arestructurally similar to first and second intermediate segments 924, 926.

As further shown in FIGS. 9A-9B, the adjunct 900 includes first, second,third, and fourth additional fibers 932, 934, 936, 938 that formrespective first, second, third, and fourth finished edges 940, 942,944, 946 that are configured to prevent fraying of the top and bottomlayers 906, 910 therealong, and thus fraying and/or fiber separation ofthe first fibers 908 and the second fibers 912. Each additional fiber932, 934, 936, 938 can be incorporated into the adjunct in a variety ofways to form respective finished edges 940, 942, 944, 946. The first andsecond finished edges 940, 942 are similar to first and second finishededges 834, 836 in FIGS. 8A-8B and therefore not described in detailedherein.

The third and fourth additional fibers 936, 938 can be incorporated intothe adjunct 900 in a variety of ways to form the third and fourthfinished edges 944, 946. In this illustrated embodiment, the thirdadditional fiber 936 interconnects the top and bottom layers 906, 910along their first outer-most lateral terminal edges 906 c, 910 c to formthe third finished edge 944. As a result, the third finished edge 944 isformed of the first fibers 908, the second fibers 912, and the thirdadditional fiber 936 and is positioned along, and thus defines, at leasta portion of a first outer-most lateral edge 948 of the adjunct 900. Thefourth additional fiber 938 interconnects the top and bottom layers 906,910 along their respective second outer-most lateral terminal edges 906d, 910 d to form the fourth finished edge 946. As a result, the fourthfinished edge 946 is formed of the first fibers 908, the second fibers912, and the fourth additional fiber 938 and is positioned along, andthus defines, at least a portion of a second outer-most lateral edge 950of the adjunct 900. Thus, at least a portion of the outer-most perimeterof the adjunct 900 is defined by the first, second, third, and fourthfinished edges 940, 942, 944, 946. In certain embodiments, for example,as shown in FIG. 9A, the outer-most perimeter of the adjunct 900 can beentirely defined by finished edges.

Further, the third additional fiber 936 and/or the fourth additionalfiber 938 can be configured as an overcast stitch. For example, asshown, the third additional fiber 936 and the fourth additional fiber938 are wrapped around the first outer-most lateral terminal edges 906c, 910 c and the second outer-most lateral terminal edges 906 d, 910 d,respectively, in the form of loops (e.g., in a spiral-typeconfiguration). As a result, the portion of free ends of the first andsecond fibers 908, 912 at the first outer-most lateral terminal edges906 c, 910 c are secured together by the third additional fiber 936 andthe portion of free ends of the first and second fibers 908, 912 at thesecond outer-most lateral terminal edges 906 d, 910 d are securedtogether by the fourth additional fiber 938. In other embodiments, thethird and fourth additional fibers 936, 938 can be configured as othersuitable stitch forms. Further, in certain embodiments, the third andfourth additional fibers 936, 938 can be configured as different stitchforms.

Alternatively, or in addition, the adjunct can include inner-mostlongitudinal terminal edge(s) relative to its outer-most longitudinalterminal edges (e.g., first and second outer-most longitudinal terminaledges 806 a, 806 b, 810 a, 810 b in FIGS. 8A-8B). In such embodiments,the adjunct can include additional fibers that are incorporated into theadjunct such that finished edge(s) can also be formed along, and thusdefine, at least a portion of the inner-most longitudinal terminaledge(s). For example. an adjunct can include inner-most longitudinalterminal edges that are configured to border a longitudinal slot, likelongitudinal slot 210 in FIGS. 2A-2C, of a staple cartridge. In suchembodiments, the adjunct can include at least one bridging element thatextends between and tethers spaced apart portions of the adjuncttogether (e.g., portions that are configured to be positioned onopposite sides of the longitudinal slot when the adjunct is coupled tothe cartridge). In certain embodiments, the at least one bridgingelement can be designed to overlap with at least a portion of a cut-lineof the adjunct, and thus at least a portion of the longitudinal slot. Asa result, the at one least bridging element is severed by theadvancement of the cutting element through the longitudinal slot.

In some embodiments, the at least one bridging element can include twoor more bridging elements that are spaced apart relative to each otherto provide discrete attachments between portions of the adjunct. Inembodiments where such portions are configured to be positioned onopposite sides of the longitudinal slot of the cartridge, the discreteattachments can reduce the amount of adjunct material positioned withinthe advancement path of the cutting element. This material reduction canhelp to minimize the resistance of the adjunct to the advancement of thecutting element which, among other things, can improve the life of thecutting element and/or reduce the force required to advance the cuttingelement through the adjunct. In certain embodiments, the at least onebridging element can be formed of a portion of at least one of the topand bottom layers of the adjunct, whereas in other embodiments, the atleast bridging element can be formed of separate material.Alternatively, one or more of the at least one bridging element can bepositioned outside the advancement path of the cutting element, andthus, can continue to tether the portions of the adjunct after thecutting element is advanced through the longitudinal slot.

FIGS. 10A-10D show another exemplary embodiment of a stapling assembly1000 having a staple cartridge 1002 and a knitted adjunct 1004 that isdisposed on a top or deck surface 1003 of the staple cartridge 1002 andthat has one or more finished edges. The staple cartridge 1002 issimilar to staple cartridge 200 in FIGS. 1-2C, and therefore commonfeatures are not described in detail herein. Further, aside from thedifferences described below, the adjunct 1004 is similar to adjunct 804in FIGS. 8A-8B, and therefore common features are not described indetail herein.

The adjunct 1004 can have a variety of configurations. For example, inthis illustrated embodiment, the adjunct 1004 includes first and secondlongitudinal portions 1006, 1008, each having a respective top layer1010, 1012 (e.g., a tissue-contacting layer) formed of first fibers1014, a bottom layer 1016, 1018 (e.g., a cartridge-contacting layer)formed of second fibers 1020, and spacer fibers 1022 that areintertwined with and that extend between the respective top and bottomlayers 1010, 1012, 1016, 1018 to thereby connect the top and bottomlayers. The top and bottom layers 1010, 1012 are similar in structure tothe top and bottom layers 806, 810 in FIGS. 8A-8B and the spacer fibers1022 are similar to the spacer fibers 814 in FIGS. 8A-8B, and thereforecomment features are not described in detail herein. Further, at leastof a portion of the fibers in the first longitudinal portion 1006 can bethe same or different than at least a portion of the fibers of thesecond longitudinal portion 1008. In this illustrated embodiment, thefirst fibers 1014 in the first and second longitudinal portions 1006,1008 are the same type of fibers, the second fibers 1020 in the firstand second longitudinal portions 1006, 1008 are the same type of fibers,and the spacer fibers 1022 in the first and second longitudinal portions1006, 1008 are the same type of fibers.

The first and second longitudinal portions 1006, 1008 can each includeadditional fibers that form a respective finished edge configured toprevent fraying of the respective top and bottom layers 1010, 1012therealong, and thus fraying and/or fiber separation of the first fibers1014 and the second fibers 1020. As shown in greater detail in FIG. 10B,the first longitudinal portion 1006 includes eight additional thirdfibers 1024 a, 1024 b, 1024 c, 1024 d, 1024 e, 1024 f, 1024 g, 1024 h,and the second longitudinal portion 1008 includes eight additionalfourth fibers 1026 a, 1026 b, 1026 c, 1026 d, 1026 e, 1026 f, 1026 g,1026 h. Consequently, the first longitudinal portion 1006 includesfinished edges 1028 a, 1028 b, 1028 c, 1028 d, 1028 e, 1028 f, 1028 g,1028 h, and the second longitudinal portion 1008 includes finished edges1030 a, 1030 b, 1030 c, 1030 d, 1030 e, 1030 f, 1030 g, 1030 h. Whilethe first and second longitudinal portions 1006, 1008 are eachillustrated as having eight additional third and fourth fibers 1024 a,1024 b, 1024 c, 1024 d, 1024 e, 1024 f, 1024 g, 1024 h, 1026 a, 1026 b,1026 c, 1026 d, 1026 e, 1026 f, 1026 g, 1026 h, respectively, andconsequently eight respective finished edges 1028 a, 1028 b, 1028 c,1028 d, 1028 e, 1028 f, 1028 g, 1028 h, 1030 a, 1030 b, 1030 c, 1030 d,1030 e, 1030 f, 1030 g, 1030 h, a person skilled the art will appreciatethat the amount of additional fibers can depend at least upon the sizeand shape of the staple cartridge and/or anvil to which the adjunct willbe applied, and therefore, the first and second longitudinal portions1006, 1008 are not limited to the number of additional fibersillustrated in the figures.

The additional third and fourth fibers 1024 a, 1024 b, 1024 c, 1024 d,1024 e, 1024 f, 1024 g, 1024 h, 1026 a, 1026 b, 1026 c, 1026 d, 1026 e,1026 f, 1026 g, 1026 h can have a variety of configurations. In someembodiments, two or more of the additional fibers can be generallyidentical (nominally identical within manufacturing tolerances) incompositional makeup (e.g., formed of the same material(s)),dimension(s) (e.g., height and/or diameter), and/or in structuralconfiguration (e.g., monofilament or multifilament). In certainembodiments, at least one of the additional fibers can be a monofilamentfiber. Alternatively, or in addition, at least one of the additionalfibers can be a multifilament fiber. In one embodiment, one portion ofthe additional fibers are monofilament fibers and the other portion ismultifilament fibers. As such, aside from the general overall shape, thespecific structural configuration of each of the additional third andfourth fibers 1024 a, 1024 b, 1024 c, 1024 d, 1024 e, 1024 f, 1024 g,1024 h, 1026 a, 1026 b, 1026 c, 1026 d, 1026 e, 1026 f, 1026 g, 1026 his not shown.

Further, as shown, the additional third fibers 1024 a, 1024 b, 1024 c,1024 d, 1024 e, 1024 f, 1024 g, 1024 h are similar in structure andstitch form to the additional fourth fibers 1026 a, 1026 b, 1026 c, 1026d, 1026 e, 1026 f, 1026 g, 1026 h, and therefore for sake of simplicity,the following description is with respect to the additional third fibers1024 a, 1024 b, 1024 c, 1024 d, 1024 e, 1024 f, 1024 g, 1024 h. A personskilled in the art will understand, however, that the followingdiscussion is also applicable to the additional fourth fibers 1026 a,1026 b, 1026 c, 1026 d, 1026 e, 1026 f, 1026 g, 1026 h.

The additional third fibers 1024 a, 1024 b, 1024 c, 1024 d, 1024 e, 1024f, 1024 g, 1024 h can be incorporated into the first longitudinalportion 1006 in a variety of ways to form respective finished edges 1028a, 1028 b, 1028 c, 1028 d, 1028 e, 1028 f, 1028 g, 1028 h. In thisillustrated embodiment, as shown in more detail in FIG. 10C, the firstadditional third fiber 1024 a is configured as an overcast stitch andinterconnects the top and bottom layers 1010, 1016 along their firstouter-most longitudinal terminal edges 1010 a, 1016 a to form the firstfinished edge 1028 a. As a result, the first finished edge 1028 a of thefirst longitudinal portion 1006 is formed of the first fibers 1014, thesecond fibers 1020, and the first additional third fiber 1024 a and ispositioned along, and thus defines, at least a portion of an outer-mostlongitudinal edge 1032 of the first longitudinal portion 1006. Eachremaining additional third fiber 1024 b, 1024 c, 1024 d, 1024 e, 1024 f,1024 g, 1024 h is also configured as an overcast stitch andinterconnects the top and bottoms layers 1010,1016 along a respectiveportion of a second outer-most longitudinal terminal edge 1010 b, 1014 bof the top and bottom layers 1010, 1016 to form respective and discretefinished edges 1028 b, 1028 c, 1028 d, 1028 e, 1028 f, 1028 g, 1028 h.As a result, each remaining finished edge 1028 b, 1028 c, 1028 d, 1028e, 1028 f, 1028 g, 1028 h is formed of the first fibers 1014, the secondfibers 1020, and respective additional third fiber 1024 b, 1024 c, 1024d, 1024 e, 1024 f, 1024 g, 1024 h, and is positioned along, and thusdefines, a respective portion of an inner-most longitudinal edge 1034 ofthe first longitudinal portion 1006.

As further shown, the adjunct 1004 includes bridging elements 1036 a,1036 b, 1036 c, 1036 d, 1036 e, 1036 f that extend between and connectthe first and second longitudinal portions 1006, 1008 of the adjunct1004 together. While the adjunct 1004 is illustrated as having sixbridging elements 1036 a, 1036 b, 1036 c, 1036 d, 1036 e, 1036 f, aperson skilled the art will appreciate that the number and structuralconfiguration of the bridging element(s) of the adjunct can depend atleast upon the size and shape of the staple cartridge and/or anvil towhich the adjunct will be applied and/or the size and shape of alongitudinal slot (e.g., a knife slot) within the cartridge, andtherefore, the adjunct 1004 is not limited to the number and/orstructural configuration of the bridging elements illustrated in thefigures.

The bridging elements 1036 a, 1036 b, 1036 c, 1036 d, 1036 e, 1036 f canhave a variety of configurations. For example, in illustratedembodiment, discrete portions of the first and second fibers 1014, 1020extend between the first and second longitudinal portions 1006, 1008,and as a result, these portions serve as the bridging elements 1036 a,1036 b, 1036 c, 1036 d, 1036 e, 1036 f. This creates a centralized zone1040 within the adjunct that is formed of only the first and secondfibers 1014, 1020. This results in a lesser amount of material along thecut-line of the adjunct compared to the other portions of the adjunct.In some embodiments, a portion of the spacer fibers can be presentwithin the centralized zone (e.g., the spacer fiber density within thecentralized zone is less than the spacer fiber densities within otherportions of the adjunct).

As shown in FIGS. 10A-10D, when the adjunct 1004 is releasably securedto the cartridge 1002, the first longitudinal portion 1006 is positionedon a first side of the longitudinal slot 1007 of the cartridge 1002 andthe second longitudinal portion 1008 is positioned on a second, oppositeside of the longitudinal slot 1007. With respect the first longitudinalportion 1006, the first finished edge 1028 a is positioned proximate toand along a portion of a first outer-most longitudinal edge 1005 a ofthe top surface 1003 of the cartridge 1002, and each of the remainingfinished edges 1028 b, 1028 c, 1028 d, 1028 e, 1028 f, 1028 g, 1028 hare positioned proximate to and along a respective portion of a firstslot edge 1007 a of the longitudinal slot 1007. Similarly, with respectto the second longitudinal portion 1008, the first finished edge 1030 ais positioned proximate to and along a portion of a second outer-mostlongitudinal edge 1005 b of the top surface 1003 of the cartridge 1002,and each of the remaining finished edges 1030 b, 1030 c, 1030 d, 1030 e,1030 f, 1030 g, 1030 h are positioned proximate to and along arespective portion of a second slot edge 1007 b of the longitudinal slot1007. Further, as shown in more detail in FIGS. 10B and 10D, thebridging elements at least partially overlap with the longitudinal slot1007 of the cartridge 1002.

While not shown in FIGS. 10A-10D, in certain embodiments, the adjunctcan also include one or more attachment features that extend at leastpartially along the length of adjunct (e.g., extending in thez-direction) and that are configured to engage the staple cartridge tothereby retain the adjunct on the cartridge prior to staple deployment.The one or more attachment features can have a variety ofconfigurations. For example, the one or more attachment features can bechannel attachments that are configured to engage (e.g., press-fit orsnap into) the longitudinal slot (e.g., knife slot) formed betweenopposing longitudinal slot edges in the staple cartridge.

In other embodiments, instead of incorporating additional fiber(s) intothe adjunct (e.g., additional fibers 830, 832 in FIGS. 8A-8B) forcreating one or more finished edges of the adjunct, the existing fibersof the adjunct (e.g., first fibers 1102, second fibers 1104, and spacerfibers 1106 in FIGS. 11A-11B) can be intertwined together.Alternatively, or in addition, heat can be applied to at least a portionof the existing fibers. For example, a hot blade could be used to melt,and thus fuse, at least a portion of the existing fibers, e.g., along atleast a portion of the perimeter of the adjunct. This can avoid the needfor additional material (e.g., additional fiber(s) other than the fibersneeded to form the top, bottom, and core layers of the adjunct), andthus, among other things, can decrease the overall material cost and/ormanufacturing cost of the adjunct.

FIGS. 11A-11B is one exemplary embodiment of a knitted adjunct 1100having at least one finished edge formed of fibers that also form otherportions of the adjunct. In this illustrated embodiment, the adjunct1100 includes first fibers 1102, second fibers 1104, and spacer fibers1106 that are intertwined to form a top layer 1110 (e.g., atissue-contacting layer), a bottom layer 1112 (e.g., acartridge-contacting layer), and at least one finished edge (only threefinished edges 1114 a, 1114 b, 1114 c are illustrated) extending betweenthe top and bottom layers 1110, 1112. For sake of simplicity, only onefirst fiber 1102, second fiber 1104, and spacer fiber 1106 isillustrated in FIG. 11B. A person skilled in the art will appreciatethat the following discussion is also applicable to the remaining first,second, and spacer fibers of the adjunct.

The first fibers 1102, the second fibers 1104, and the spacer fibers1106 can have a variety of configurations. For example, in someembodiments, the first fibers 1102, the second fibers 1104, and thespacer fibers 1106 can be generally identical (e.g., nominally identicalwithin manufacturing tolerances) in compositional makeup (e.g., formedof the same material(s)), dimension(s) (e.g., height and/or diameter),and/or in structural configuration (e.g., monofilament ormultifilament), whereas in other embodiments, they can be different. Incertain embodiments, the first and second fibers 1102, 1104 can begenerally identical (e.g., nominally identical within manufacturingtolerances) and the spacer fibers 1106 can be different. For example, incertain embodiments, the first and second fibers 1102, 1104 aremultifilament fibers, and the spacer fibers 1106 are monofilamentfibers. As such, aside from the general overall shape, the specificstructural configuration of each of the first fibers 1102, the secondfibers 1104, and the spacer fibers 1106 is not shown.

The top and bottom layers 1110, 1112 can have a variety of structuralconfigurations. As shown in more detail in FIG. 11B, the first fibers1102 and the spacer fibers 1106 are intertwined to form the top layer1110 and the second fibers 1104 and the spacer fibers 1106 areintertwined to form the bottom layer 1112. Thus, in this illustratedembodiment, the first fibers 1102 are not present in the bottom layer1112 and the second fibers 1104 are not present in the top layer 1110.In other embodiments, at least a portion of the first fibers 1102 can bepresent within the bottom layer 1112 and/or at least a portion of thesecond fibers 1104 can be present within the top layer 1110.

In some embodiments, the first fibers 1102 of the top layer 1110 and/orsecond fibers 1104 of the bottom layer 1112 can be knitted in arespective predetermined pattern. In certain embodiments, thepredetermined pattern of the first fibers 1102 within the top layer 1110and the predetermined pattern of the second fibers 1104 of the bottomlayer 1112 can be generally identical (e.g., nominally identical withinmanufacturing tolerances), whereas in other embodiments, thepredetermined patterns can be different. While the first fibers 1102 ofthe top layer 1110 and the second fibers 1104 of the bottom layer 1112can each be knitted in various patterns, in certain embodiments, thefirst fibers 1102 can be knitted into a first Raschel knit pattern andthe second fibers 1104 can be knitted into a second Raschel knit patternthat is the same or different than the first Rachel knit pattern.Further, in some embodiments, the fiber density of the top layer 1110can be different than the fiber density of the bottom layer 1112. Aperson skilled in the art will appreciate that the first fibers 1102 andthe second fibers 1104 can be randomly or repeatedly knitted or wovenwithin the top and bottom layers 1110, 1112, respectively. As such, andfor sake of simplicity, the top and bottom layers 1110, 1112 aregenerally illustrated, and thus the specific structural configurationsof the top and bottom layers 1110, 1112 are not limited to what isdepicted in the figures.

The portions of the spacer fibers 1106 that extend between the top andbottom layers 1110, 1112 can form an intermediate layer 1116, and thus,are positioned between the top and bottom layers 1110, 1112. While theseportions can have a variety of configurations, in this illustratedembodiment, as shown in FIG. 11B, they are arranged in such a mannerthat form standing fibers 1118. The standing fibers 1118 can beconfigured to bend or compress in response to force being applied to theadjunct 1100.

The standing fibers 1118 can have a variety of orientations within theintermediate layer. For example, in some embodiments, as shown in FIG.11B, the standing fibers 1118 have a general columnar configuration,meaning they are generally oriented in adjacent columns. In otherembodiments, the standing fibers 1118 can be angled or slanted to favoran organized collapse or bend in a first direction in response toforce(s) applied to the adjunct (e.g., compressive forces through tissue(T) positioned against the top layer 1110). Alternatively, the standingfibers 1118 can be angled or slanted to favor an organized collapse in asecond direction opposite the first direction in response to the appliedforce(s). Alternatively, the standing fibers 1118 can include a firstgroup that are angled or slanted to favor bending in the first directionand a second group of the standing fibers that are angled or slanted tofavor bending in the second direction.

As further shown in FIGS. 11A-11B, the adjunct 1100 includes fourfinished edges (only three finished edges 1114 a, 1114 b, 1114 c areillustrated) in which each finished edge extends between the top andbottom layers 1110, 1112. Further, one or more of the finished edges1114 a, 1114 b, 1114 c can be positioned at least partially along, andthus at least partially define, an outer-edge of the adjunct 1100. Forexample, in this illustrated embodiment, the adjunct 1100 has fourouter-most edges (only three outer-most edges 1120 a, 1120 b, 1120 c) inwhich the first finished edge 1114 a is positioned entirely along thefirst outer-most edge 1120 a, the second finished edge 1114 b ispositioned entirely along the second outer-most edge 1120 b, the thirdfinished edge 1114 c is positioned entirely along the third outer-mostedge 1120 c, and the fourth finished edge (obstructed) is positionedentirely along the fourth outer-most edge (obstructed). As a result, thefour finished edges define the entire outer-most perimeter of theadjunct 1100.

Each finished edge is formed of respective portions of the first fibers1102, the second fibers 1104, and the spacer fibers 1106. The firstfibers 1102, the second fibers 1104, and the spacer fibers 1106 caninteract in a variety of ways to effect the finished edges. In thisillustrated embodiment, each finished edge is structurally similar andincludes respective portions of the first fibers, the second fibers, andthe spacer fibers intertwined together. While only the first and secondfinished edges are illustrated in detail, a person skilled in the artwill appreciate the following discussion is also applicable to the thirdfinished edge 1114 c and the fourth finished edge.

As shown in greater detail in FIG. 11B, the first finished edge 1114 aincludes a first portion 1122 a of the first fibers 1102, a firstportion 1124 a of the second fibers 1104, and a first portion 1126 a ofthe spacer fibers 1106 that are intertwined together. In addition, thefree ends 1128 a of the first portion 1122 a of the first fibers 1102,the free ends 1130 a of the first portion 1124 a of the second fibers1104, and the free ends 1132 a of the first portion 1126 a of the spacerfibers 1106 can be knotted together, as shown in FIG. 11B. Similarly, asshown in FIG. 11B, the second finished edge 1114 b includes a secondportion 1122 b of the first fibers 1102, a second portion 1124 b of thesecond fibers 1104, and a second portion 1126 b of the spacer fibers1106 that are intertwined together. In addition, the free ends 1128 b ofthe second portion 1122 b of the first fibers 1102, the free ends 1130 bof the second portion 1124 b of the second fibers 1104, and the freeends 1132 b of the second portion 1126 b of the spacer fibers 1106 canbe knotted together, as shown in FIG. 11B.

While not shown, in certain embodiments, the adjunct 1100 can alsoinclude additional finished edge(s) that are configured to be positionedadjacent to and along a respective slot edge of a longitudinal slotformed within a cartridge to which the adjunct is intended to bereleasably attached thereto. In such embodiments, for example, at leastone additional finished edge can be formed of respective portions of thefirst fibers 1102, the second fibers 1104, and the spacer fibers 1106.

While the adjuncts 804, 900, 1004 in FIGS. 8A-10D each include finishededges that are formed by additional fibers, and the adjunct 1100 inFIGS. 11A-11B includes finished edges that are formed by existingfibers, in other embodiments, an adjunct can have a combination ofdifferent types of finished edges. For example, in certain embodiments,an adjunct can have at least one finished edge that is formed by anadditional fiber(s) (e.g., first finished edge 34 in FIG. 8B) and atleast one finished edge that is formed by a portion of existing fibersotherwise present in the adjunct (e.g., first finished edge 1114 a inFIGS. 11A-11B).

Alternatively, or in addition, the adjunct can include an absorbablefilm that is disposed over at least a portion of a tissue-facing surfaceof an outer layer and/or inner layer. The absorbable film cansubstantially protect the fibers of the underlying layer(s) from beingexposed to forces that would otherwise lead to fraying, pulling, and/orseparating. For example, in certain embodiments, an absorbable film canbe used to form at least a portion of one or more finished edges of theadjunct. Further, the absorbable film can substantially prevent tissuefrom causing the adjunct to prematurely detach from the cartridge whilethe tissue slides across the adjunct. That is, the absorbable film canminimize edge conditions, and thus decrease the friction that wouldotherwise be present on the tissue-contacting surface(s) of the adjunct.

The absorbable film can have a variety of configurations. In someembodiments, the absorbable film can have a thickness that is less thanor equal to about 15 microns, e.g., from about 5 microns to 15 microns,or from about 8 microns to 11 microns. In one embodiment, the absorbablefilm can be formed of polydioxanone. The absorbable film can be attachedto a knitted structure in a variety of ways. For example, in oneembodiment, the absorbable film can be attached by heating the film(e.g., equal to or above a glass transition temperature of the filmmaterial) and then pressing the film onto the knitted structure tothereby create a bond therebetween. Alternatively, at least a portion ofthe knitted structure (e.g., a portion of the fibers of the bottomlayer) can be heated (e.g., above 85° C.) and then pressed against thefilm.

FIG. 12 illustrates one exemplary embodiment of a stapling assembly 1200that includes a staple cartridge 1202 and a knitted adjunct 1204disposed on a top or deck surface 1203 of the cartridge 1202. The staplecartridge 1202 is similar to staple cartridge 200 in FIGS. 1-2C, andtherefore common features are not described in detail herein.

The adjunct 1204 includes a knitted structure 1206 with an absorbablefilm 1208 disposed on at least a portion thereof. The knitted structureincludes a top layer 1210, a bottom layer 1212, and a core layer 1214extending therebetween. The top layer 1210, the bottom layer 1212, andthe core layer 1214 are similar to the top layer 1110, the bottom layer1112, and the intermediate layer 1116 in FIGS. 11A-11B, and thereforecommon features are not described herein. As shown, the absorbable film1208 is disposed on all tissue-facing surfaces of the knitted structure1206, which, in this illustrated embodiment, includes a top-tissuefacing surface 1216 (e.g., extending in the YZ plane), a firstlongitudinal side surface 1218 a (e.g., extending in the XZ plane), asecond opposing longitudinal side surface 1218 b, a first lateral sidesurface 1220 a (e.g., extending in the XY plane), and a second opposinglateral side surface (obstructed). In other embodiments, the absorbablefilm is not disposed on all tissue-facing surfaces of the knittedstructure, e.g., the first lateral side surface and/or the secondlateral side surface.

Attachment Features

In general, the knitted adjuncts described herein are designed andpositioned atop a staple cartridge for use in a stapling procedure. Whenthe staples are fired (deployed) from the cartridge, the staplespenetrate through the adjunct and into tissue. Prior to the adjunctbeing penetrated by the staples, the adjunct may become dislodged ormisaligned from the staple cartridge. That is, when the staple cartridgeis being placed into position, the adjunct may be dislodged by cominginto contact with a portion of a surgical site. In order to keep theadjunct aligned and secured on the staple cartage prior to firing thestaples, one or more surfaces features may be arranged within theadjunct. The one or more surface features (e.g., one or more recesses)may be woven, thermoformed, or mechanically positioned within theadjunct.

As discussed above, the knitted adjuncts are formed of fibers that areknitted or woven together. In certain embodiments, the adjuncts can bedesigned such that one or more surface features can be formed within theadjunct. The one or more surface features are configured tosubstantially, or completely, align and secure the adjunct to thecartridge deck prior to staple deployment. As a result, the adjunct canremain secured to the cartridge deck when exposed to forces that wouldotherwise cause the adjunct to separate from the cartridge deck prior tostapling of the adjunct to tissue. The one or more surface features canalso decrease the likelihood of misalignment of the adjunct prior tostapling, as compared to conventional adjuncts (e.g., adjuncts withoutone or more surface features).

The one or more surface features can be formed in a variety of ways. Forexample, in some embodiments, the surface features can be created in theadjunct after fabrication. For example, using a solvent, a knittingoperation, a heat operation, a die cutting operation, a laser cuttingoperation, an ultrasonic cutting operation, a stamping or punchingoperation (e.g., a mechanical pressing), or a combination of thesetechniques. In some embodiments, the surface features can be knittedinto the bottom-most layer (e.g., cartridge-contacting layer) of theadjunct. In other embodiments, the surface features can be thermoformedin the adjunct using a heated mold. Alternatively, or in addition to,the surface features can be thermoformed in the adjunct by heating thestapling cartridge and positioning the adjunct onto the heated cartridgedeck so that the adjunct conforms to the shape of the cartridge deck,including any one or more attachment features (e.g., projections) of thecartridge deck.

In some embodiments, the one or more surface features can have a minimumdiameter that is smaller than the diameter of the staple legs.Alternatively, or in addition, the one or more surface features a canhave maximum diameter that is greater than the circumference (e.g.,outer diameter) of the one or more attachment features of the cartridgeto form a friction or press-fit. In certain embodiments, the one or moresurface features can be sized so as to receive two or more attachmentfeatures of the cartridge.

FIG. 13A illustrates a portion of another exemplary embodiment of astapling assembly 1300 that includes a knitted adjunct 1302 disposed ona top or deck surface 1306 of a staple cartridge 1304, with FIG. 13Billustrating the adjunct and the cartridge prior to being releasablycoupled together. The adjunct 1302 includes a first knitted layer 1308(e.g., a top or tissue-contacting layer) formed of at least first fibers1310, a second knitted layer 1312 (e.g., a bottom orcartridge-contacting layer) formed of at least second fibers 1314, andspacer fibers 1316 intertwined with and extending between the first andsecond knitted layers 1308, 1312 to thereby connect the first and secondknitted layers 1308, 1312 together. The portions of the spacer fibers1316 that extend between the first and second knitted layers 1308, 1312form a core layer 1318 of the adjunct 1302. For sake of simplicity, onlyone first fiber 1310, second fiber 1314, and spacer fiber 1316 is beingillustrated. A person skilled in the art will appreciate that thefollowing discussion is also applicable to the remaining first, second,and spacer fibers of the adjunct.

In some embodiments, the first fibers 1310 of the first knitted layer1308 can be knitted or woven into a first predetermined pattern and/orthe second fibers 1314 of the second knitted layer 1312 can be knittedor woven into a second predetermined pattern. In certain embodiments,the first and second predetermined patterns can be generally identical(e.g., nominally identical within manufacturing tolerances), whereas inother embodiments, the first and second predetermined patterns can bedifferent. Further, in some embodiments, the fiber density of the firstknitted layer 1308 can be different than the fiber density of the secondknitted layer 1312. While the first fibers 1310 and the second fibers1314 can be knitted or woven in various patterns, in certainembodiments, the first fibers 1310 can be knitted into a first Raschelknit pattern and the second fibers 1314 can be knitted into a secondRaschel knit pattern that is the same or different than the firstRaschel knit pattern. A person skilled in the art will appreciate thatthe first fibers 1310 and the second fibers 1314 can be randomly orrepeatedly knitted or woven within the first and second knitted layers1308, 1312, respectively. As such, and for sake of simplicity, the firstand second knitted layers 1308, 1312 are generally illustrated, and thusthe specific structural configurations of the first and second knittedlayers 1308, 1312 are not limited to what is depicted in the figures.

The first fibers 1310, the second fibers 1314, and the spacer fibers1316 can have a variety of configurations. For example, in someembodiments, the first fibers 1310, the second fibers 1314, and thespacer fibers 1316 can be generally identical (e.g., nominally identicalwithin manufacturing tolerances) in compositional makeup (e.g., formedof the same material(s)), dimension(s) (e.g., height and/or diameter),and/or in structural configuration (e.g., monofilament ormultifilament), whereas in other embodiments they are different. Inother embodiments, the first and second fibers 1310, 1314 can begenerally identical (e.g., nominally identical within manufacturingtolerances) and the spacer fibers 1316 can be different. For example, incertain embodiments, the first and second fibers 1310, 1314 can bemultifilament fibers, and the spacer fibers 1316 can be monofilamentfibers. As such, aside from the general overall shape, the specificstructural configuration of each of the first fibers 1310, the secondfibers 1314, and the spacer fibers 1316 is not shown.

As further shown in FIG. 13B, which the adjunct includes one or moresurface features formed within the second knitted layer 1312, which inthis illustrated embodiment are in the form of recesses (only tworecesses 1322 a, 1322 b are being illustrated). The one or more recessesare configured to receive and engage respective attachment features ofthe cartridge 1304, as shown in FIG. 13A, which in this illustratedembodiment are in the form of projections 1324 a, 1324 b that eachextend outward from the top or deck surface 1306 of the cartridge 1304.The recesses 1322 a, 1322 b can be formed by manipulating portions ofthe second fibers 1314 within the second knitted layer 1312 (e.g.,melting or further knitting). In this illustrated embodiment, theperimeter of the recesses 1322 a, 1322 b are defined by melted portionsof the second fibers 1314.

The recesses 1322 a, 1322 b and projections 1324 a, 1324 b can havevariety of configurations. For example, in this illustrated embodiment,the recesses 1322 a, 1322 b have an inverted conical-shape, andtherefore a varying diameter that decreases as the recesses 1322 a, 1322b extends into the second knitted layer 1312. As such, each recess 1322a, 1322 b extends from a maximum diameter X_(1a), X2 a. to a minimumdiameter X_(1b), X_(2b). Further, the projections 1324 a, 1324 b have aconical-shaped with a varying diameter that decreases as the projections1324 a, 1324 b extend outward from the top or deck surface 1306. Assuch, each projection extends 1324 a, 1324 b from a maximum diameterX_(1c), X_(1c) to a minimum diameter X_(2c), X_(2d). While the recesses1322 a, 1322 b and projections 1324 a, 1324 b are illustrated as havingcomplementary conical-shapes, a person skilled in the art willappreciate that the recesses can have other complementary shapes, suchas squares, half-circles, triangles, etc. Further, while the recesses1322 a, 1322 b are illustrated as being generally uniform (e.g., uniformwithin manufacturing tolerances), in other embodiments, at least aportion of the recesses can differ.

The difference between the maximum diameters X_(1a), X_(1b) and themaximum diameters X_(2a), X_(2b) can allow for a friction fit to beformed between the recesses 1322 a, 1322 b and the projections 1324 a,1324 b. In this illustrated embodiment, the maximum diameters of therecesses 1322 a, 1322 b are smaller than the maximum diameters of theprojections 1324 a, 1324 b prior to the engagement. As a result, aninterference fit can be created between the portions of the secondfibers 1314 that contact the projections 1324 a, 1324 b. This frictionforce can aid in securing the adjunct 1302 to the staple cartridge 1304.In other embodiments, the maximum diameters of the recesses 1322 a, 1322b can be larger than the maximum diameters of the projections 1324 a,1324 b prior to the engagement.

Further, while not shown, the minimum diameters X_(1a), X_(1b) of therecesses 1322 a, 1322 b within the adjunct 1302 can be smaller than thediameter of staple legs (e.g. maximum diameter of the wire that formsthe staple legs) that at least partially disposed within the staplecartridge 1304. As a result, when the adjunct 1302 is releasably coupledto the cartridge 1304, and the recesses 1322 a, 1322 b are alsoconfigured to overlap with the staple cavities of the cartridge 1304,like staple cavities 212, 214 in FIGS. 2A-2C, the portions of the staplelegs extending beyond the top or deck surface 1306 of the cartridge 1304can also engage the recesses of the adjunct 1302. This can also create afriction fit therebetween and further secure the adjunct to the staplecartridge prior to staple deployment.

As further shown in FIG. 13B, due to the spaced apart arrangement of therecesses 1322 a, 1322 b in the second knitted layer 1312, a projection1326 is formed between the recesses 1322 a, 1322 b with a maximumdiameter of D₁. Additionally, due to the spaced arrangement of theprojections 1324 a, 1324 b on the top surface 1306 of the cartridge1304, a complementary recess 1328 is formed between the projections 1326b, 1326 b with a maximum diameter of D₂. As shown in FIG. 13A, theprojection 1326 is received within and engages the recess 1328 when theadjunct 1302 is coupled to the cartridge 1304. In this illustratedembodiment, the maximum diameter D₁ of the projection 1326 is largerthan the maximum diameter D₂ of the recess 1328 prior to engagement. Asa result, this can create an additional interference fit between theadjunct 1302 and the cartridge 1304. This can also increase the frictionbetween the recesses 1322 a, 1322 b and the projections 1324 a, 1324 bas the different in diameter will push the second fibers 1314 at theperimeter of the recesses 1322 a, 1322 b further towards and against theprojections 1324 a, 1324 b (e.g., in a y-direction).

In certain embodiments, the recesses are formed in the second knittedlayer of the adjunct by thermoforming the second knitted layer on aheated mold having mold features, which are the inverse shape of thedesired shape for the recesses. The mold features are similar in shapeto the attachment features, but can be either larger or smaller than thedimensions of the attachment features. If the mold features have smallerdimensions than the attachment features, this will ensure a snug,friction fit between the adjunct and the staple cartridge.

In order to form the recesses in the adjunct, the heated mold is heatedto a specific temperature (e.g., at or above the glass transitiontemperature of the second fibers of the second knitted layer) and thenthe adjunct is pressed onto, into, and/or against the heated mold. Insome embodiments, the mold features can be the same or differentcompared to one another.

Upon engagement with the heated mold, the adjunct forms, or molds, intothe mold features of the heated mold, creating the recesses within thesecond knitted layer. The portion of the second knitted layer whichcomes into contact with the mold features of the heated mold arethermoformed into the shape of the mold features. Once the heated moldis released from the second knitted layer, the second knitted layerretains the shape of the mold features. The recesses are configured topermit the progressive release of the adjunct from the staple cartridge.One advantage of the thermoformed recesses may include having an adjunctwith a more complex shape which custom fits with a corresponding staplecartridge while sustaining a simpler manufacturing process, for example.In certain embodiments, the cartridge deck and the mold featurescorrespond to the shape of the attachment features of the staplecartridge.

In other embodiments, thermoforming of the adjunct can occur by heatingthe staple cartridge deck. The cartridge can be heated to a temperatureabove, at, or close to the glass transition temperature of the material,or materials, of the bottom layer (e.g., cartridge-contacting layer) ofthe adjunct. The adjunct can then be placed over and pushed down ontothe staple cartridge and staples disposed therein. Since the adjunct isheated to a temperature above, at, or slightly below the glasstransition temperature of material the adjunct is formed from, theadjunct can take a new permanent shape around the attachment features ofthe staple cartridge and/or around any of the staple legs extending fromthe top surface of the cartridge.

For example, the staple cartridge can include projections extending fromthe cartridge deck and, when the adjunct is pushed onto the heatedcartridge deck and attachment features, the adjunct can be permanentlydeformed around the attachment features. In such instances, the adjuncttightly grips the attachment features until the adjunct is pushed offthe attachment features by the staples. Similarly, the adjunct canpermanently deform around and tightly grip the heated staple legs. Inone embodiment, the minimum diameter of the newly-formed recesses withinthe adjunct can be smaller than the diameter of the staple legs. Duringthe forming process of the recesses, the pressure is applied to theadjunct until the temperature of the staple cartridge, the staples,and/or the adjunct is well below, or at least below, the glasstransition temperature of the materials comprising the adjunct.Alternatively, the pressure can be removed when the temperature of thestapling assembly is at or above the glass transition temperature of thematerials comprising the adjunct.

In other embodiments, an adjunct can include knitted recesses that areconfigured to receive and engaged with one or more attachment featuresof a staple cartridge. For example, the as the adjunct is knitted,portions of the second fibers of the second knitted layer can be knittedin such a way to define a perimeter of the recesses within the secondknitted layer. Alternatively, or in addition, additional fibers can beincorporated into the bottom layer so as to at least partially definethe perimeter of the recesses

Fiber Interconnectivity and Adjunct Compressibility

An adjunct is stapled to tissue under various stapling conditions (e.g.,tissue thickness, height of formed staple, intra-tissue pressure).Depending on the stapling condition, one can determine an effectiveamount of stress that the adjunct needs to be able to apply to thetissue to prevent tissue tearing and leakage. For example, in oneembodiment, an effective amount of stress is at least about 3 gf/mm². Inorder for the adjunct to provide an effective amount of stress to thetissue, the adjunct can be designed to effectively compensate for thevarious stapling conditions. As such, the adjunct can be tailored toassume different compressed heights when stapled to tissue.

The compressibility profile of the adjunct can therefore be controlledby at least the structural configuration of the fibers and theinterconnectivity between them. As a result, the structuralconfiguration of the fibers can be tailored to effect an adjunct withdesirable mechanical properties for stapling tissue. As there is afinite range of intra-tissue pressures, tissue thicknesses, and formedstaple heights, one can determine appropriate material and/or geometricstructures for the adjunct that can be effective in applying asubstantially continuous desired stress to the tissue (e.g., 3 gf/mm²)when stapled thereto for a given amount of time (e.g., at least 3 days)over a range of stapling conditions. That is, as described in moredetail below, the present adjuncts are formed of compressible materialsand geometrically configured so as to allow the adjunct to compress tovarious heights in predetermined planes when stapled to tissue. Further,this varied response by the adjunct can also allow the adjunct tomaintain its application of a continuous desired stress to the tissuewhen exposed to fluctuations in intra-tissue pressure that can occurwhen the adjunct is stapled to tissue (e.g., a spike in blood pressure).

As discussed above, the spacer fibers are intertwined with the first andsecond fibers of the top and bottom layers, respectfully, to therebyconnect the top and bottom layers in a spaced apart relation. As such,the spacer fibers are interconnected with the first fibers at firstinterconnections and with the second fibers at second interconnections.The portions of the spacers fibers that extend between the top andbottom layers thereby form an intermediate layer of the adjunct. Whilethese portions can have a variety of configurations, these portions canbe arranged in such a manner that form standing fibers. The standingfibers can be configured to bend or compress in response to force beingapplied to the adjunct. As a result, the manner in which the spacerfibers interact with the first and second fibers (e.g., the first andsecond interconnections) can control, at least in part, the standingfibers stiffness or ability to bend under compression which, in turn,controls, at least in part, the overall compressibility of the adjunct.Thus, in some embodiments, the number, location, and tightness of theinterconnections can be varied laterally, longitudinally, or thru thethickness of the adjunct to effect different stiffnesses within theadjunct.

In some embodiments, the first and second interconnections have agenerally uniform structure (e.g., nominally identical withinmanufacturing tolerances), whereas in other embodiments, the first andsecond interconnections are different. The first and secondinterconnections can have a variety of configurations. For example, insome embodiments, the first interconnections and/or the secondinterconnection can be single-looped knots. In other embodiments, thefirst interconnections and/or the second interconnections can bemulti-looped knots, for example, as shown in FIGS. 14A-17B. In certainembodiments, the first interconnections can be single-looped knots andthe second interconnections can be multi-looped knots (see FIG. 20).

The first and/or second interconnections can be in the form of anysuitable knot type. The type of knots that are used can affect thestiffness of the intermediate layer, and consequently, the compressionbehavior of the adjunct. For example, if loose knots are used, theintermediate layer can be less stiff or can have a lower modulus ofelasticity. Alternatively, if tight knots are used, the intermediatelayer can be stiffer or have a higher modulus of elasticity. Theintermediate layer can utilize any suitable type, or types, of knots.

FIGS. 14A-14B is another exemplary embodiment of a knitted adjunct 1400that includes first fibers 1402, second fibers 1404, and spacer fibers1406. For sake of simplicity, only one first fiber 1402, second fiber1404, and spacer fiber 1406 is being illustrated. A person skilled inthe art will appreciate that the following discussion is also applicableto the remaining first, second, and spacer fibers of the adjunct.

The spacer fibers 1406 and the first fibers 1402 are interconnected atfirst interconnections 1408 to form a top layer 1410. The spacer fibers1406 and the second fibers 1404 are interconnected at secondinterconnections 1412 to form a bottom layer 1414. The first and secondinterconnections 1408, 1412 can have a variety of configurations. Forexample, as shown, the first interconnections 1408 are in the form offirst knots having the spacer fibers 1406 multi-looped about the firstfibers 1402 and the second interconnections 1412 are each in the form ofsecond knots having the spacer fibers 1406 multi-looped about the secondfibers 1404. While the first and second knots 1408, 1412 are illustratedas being structurally similar, in other embodiments, the first andsecond knots can be different. Further, as described in more detailbelow, the first knots 1408 and the second knots 1412 are schematicallyillustrated as having a loose knot configuration.

Further, the portions of the spacer fibers 1406 that extend between thetop and bottom layers 1410, 1414 form an intermediate layer 1418 that ispositioned between the top and bottom layers 1410, 1414. While theseportions can have a variety of configurations, in this illustratedembodiment, they are arranged in such a manner that form standing fibers1416. The standing fibers 1416 can be have a variety of orientationswithin the intermediate layer 1418, such as a generally columnarconfiguration, as shown, meaning they are generally oriented in adjacentcolumns. The standing fibers 1416 can be configured to bend or compressin response to force being applied to the adjunct 1400, as schematicallyillustrated in FIG. 14B.

As depicted in FIG. 14B, when a given force F is applied to the adjunct1400 (e.g., in an x-direction), the spacer fibers 1406 slide along thefirst and second fibers 1402, 1404 (e.g., in a ±y-direction). Thissliding action is due to the loose knot configuration of the first andsecond knots 1408, 1412. Consequently, the standing fibers 1416 slideand causes the top layer 1410 to move towards the bottom layer 1414. Asa result, the adjunct 1400 compresses from an uncompressed state (FIG.14A) with an uncompressed height Hi to a first compressed state (FIG.14B) with a first compressed height H₂. Thus, under a given force, thesliding of the spacer fibers 1406, and consequently, the standing fibers1416, primarily effects the compression of the adjunct 1400 from theuncompressed height H to the first compressed height H₂.

In some embodiments, tighter knots can be used to interconnect thespacer fibers with the first fibers and the seconds second fibers, forexample, as shown in FIGS. 15A-15B, to thereby increase the stiffness ofthe standing fibers, and thus the stiffness of the adjunct. Adjunct 1500is similar to adjunct 1400 in FIGS. 14A-14B except that the first andsecond knots 1508, 1512 have a tighter knot configuration, and thereforecommon features are not described in detail herein.

As depicted in FIG. 15B, when a given force F is applied to the adjunct1500 (e.g., in an x-direction), the tighter configuration of the knots1508, 1512 inhibit the spacer fibers 1506 from sliding along the firstand second fibers 1502, 1504, and thus prevent the standing fibers 1516from respectively sliding. This imparts more rigidity to the standingfibers 1516, thereby increasing their stiffness. As a result, thestanding fibers 1516 are stiffer compared to the standing fibers 1416 ofFIGS. 14A-14B, and therefore this leads to a stiffer adjunct 1500 whencompared to the adjunct 1400 of FIGS. 14A-14B. For example, when thesame amount of force is applied to the adjunct 1500, the adjunct 1500compresses from an uncompressed state (FIG. 14A) with an uncompressedheight H₃ that is similar to uncompressed H₁ of adjunct 1400 to a secondcompressed state (FIG. 14B) with a second compressed H₄ that is largerthan the first compressed height H₂ of adjunct 1400. This illustratesthe impact that knot tightness can have on the compression of anadjunct.

Similarly, knot tightness can impart can impart partial rigidity tothinner spacer fibers, and thus, increase the overall stiffness of anadjunct, like adjunct 1600 in FIGS. 16A-16C. Adjunct 1600 is similar toadjunct 1500 in FIGS. 15A-15B except that the spacer fibers 1606 arethinner compared to spacer fibers 1506.

In some embodiments, the intermediate layer of an adjunct can includereinforcing fibers that are interconnected with the standing fibers,which can further increase the stiffness of the adjunct, for example, asshown in FIGS. 17A-17B. Adjunct 1700 is similar to adjunct 1500 in FIGS.15A-15B except that the standing fibers 1716 are multi-looped aboutreinforcing fibers 1720 at third interconnections 1722, in which thereinforcing fibers 1720 each extend mid-way through the intermediatelayer 1718 (e.g., extending in the y-direction). As a result, for agiven amount of force F, as shown in FIG. 17B, the adjunct 1700 willcompress from an uncompressed state (FIG. 17A) with an uncompressedheight H₅ that is similar to uncompressed H₃ of adjunct 1500 to a secondcompressed state (FIG. 17B) with a third compressed height H₆, which islarger than the second compressed height H₄ of adjunct 1500.

FIGS. 18A-18B illustrate another exemplary embodiment of a knittedadjunct 1800. The adjunct 1800 includes a layer 1802 formed of at leastfirst fibers 1808, and a core layer formed of spacer fibers 1804intertwined with and extending from the layer 1802. The layer 1802 canbe a top layer (e.g., a tissue-contacting layer) or a bottom layer(e.g., a cartridge-contacting layer) of the adjunct 1800, with portionsof the spacer fibers 1804 forming the core layer arranged between thetop and bottom layers. In this illustrate embodiment, the portions ofthe spacer fibers 1804 that form the core layer extend between the topand bottom layers in a generally columnar configuration, meaning theyare generally oriented in adjacent columns. For sake of simplicity, onlya portion of the first fibers 1808 and of the spacer fibers 1804 isbeing illustrated. A person skilled in the art will appreciate that thefollowing discussion is also applicable to the remaining first fibersand spacer fibers of the adjunct.

As shown in FIGS. 18A-18B, the spacer fibers 1804 extend along a centralaxis CA, outward from the layer 1802. The layer 1802 includesreinforcing fibers 1806, which are knotted to the spacer fibers 1804 andthe first fibers 1808. The knotting of the reinforcing fibers 1806 canlimit the lateral movement LM of the spacer fibers 1804 from the centralaxis CA of each spacer fiber 1804. This interaction between the spacerfibers 1804 and the reinforcing fibers 1806 affects the stiffness of theadjunct 1800. Since the spacer fibers 1804 have limited lateral movementLM, the spacer fibers 1804 have limited deformation abilities when theadjunct 1800 is compressed.

FIGS. 19A-19B illustrate another exemplary embodiment of a knittedadjunct 1900. The adjunct 1900 can be disposed on a top or deck surfaceof a staple cartridge. The adjunct 1900 includes a layer 1902 formed ofat least first fibers 1908, and a core layer formed of spacer fibers1904 intertwined with and extending from the layer 1902. The layer 1902can be a top layer (e.g., a tissue-contacting layer) or a bottom layer(e.g., a cartridge-contacting layer) of the adjunct 1900, with thespacer fibers 1904 forming the core layer arranged between the top andbottom layers. In this illustrated embodiment, the portions of thespacer fibers 1904 that form the core layer extend between the top andbottom layers in a generally columnar configuration, meaning they aregenerally oriented in adjacent columns. For sake of simplicity, only aportion of the first fibers 1908 and of the spacer fibers 1904 is beingillustrated. A person skilled in the art will appreciate that thefollowing discussion is also applicable to the remaining first fibersand spacer fibers of the adjunct.

As shown in FIGS. 19A-19B, the spacer fibers 1904 extend along a centralaxis CA, outward from the layer 1902. The layer 1902 does not includeany reinforcing fibers in contact with the spacer fibers 1904. Due tothe lack of reinforcing fibers, the spacer fibers are less limited intheir lateral movement LM from the central axis CA of each spacer fiber1904 when compared to the adjunct 1800 of FIG. 18A. This interactionbetween the spacer fibers 1904 and the first fibers 1908, with anyreinforcing fibers, affects the stiffness of the adjunct 1900. Since thespacer fibers 1904 have extended lateral movement LM, the spacer fibers1904 have greater deformation abilities when compared to the adjunct1800 of FIG. 18A when the adjunct 1900 is compressed.

FIG. 20 illustrates another exemplary embodiment of a knitted adjunct2000. The adjunct 2000 includes a top layer 2002 (e.g., atissue-contacting layer) formed of at least first fibers 2008, a bottomlayer 2004 (e.g., a cartridge-contacting layer) formed of at leastsecond and third fibers 2012, 2014 and spacer fibers 2016 intertwinedwith and extending between the top and bottom layers 2002, 2004 tothereby connect the top and bottom layers 2002, 2004. The portions ofthe spacer fibers 2016 that extend between the top and bottom layers2002, 2004 form a core layer 2006. For sake of simplicity, only onefirst fiber 2008, second fiber 2012, third fiber 2014, and spacer fiber2016 is being illustrated. A person skilled in the art will appreciatethat the following discussion is also applicable to the remaining first,second, third, and spacer fibers of the adjunct.

The top and bottom layers 2002, 2004 can have a variety ofconfigurations. For example, as shown in FIG. 20, the bottom layer 2004has a fiber density that is greater than the fiber density of the toplayer 2002. In other embodiments, the top layer 2002 can have a greaterfiber density than the bottom layer 2004. In some embodiments, the firstfibers 2008 of the top layer 2002 can be knitted or woven into a firstpredetermined pattern and/or the second and third fibers 2012, 2014 ofthe bottom layer 2004 can be knitted or woven into a secondpredetermined pattern. In certain embodiments, the first and secondpredetermined patterns can be generally identical (e.g., nominallyidentical within manufacturing tolerances), whereas in otherembodiments, the first and second predetermined patterns can bedifferent. A person skilled in the art will appreciate that the firstfibers 2008 and the second and third fibers 2012, 2014 can be randomlyor repeatedly knitted or woven within the top and bottom layers 2002,2004, respectively. As such, and for sake of simplicity, the top andbottom layers 2002, 2004 are generally illustrated, and thus thespecific structural configurations of the top and bottom layers 2002,2004 are not limited to what is depicted in the figures.

The first fibers 2008, the second fibers 2012, the third fibers, 2014and the spacer fibers 2016 can have a variety of configurations. Forexample, in some embodiments, the first fibers 2008, the second fibers2012, the third fibers 2014, and the spacer fibers 2016 can be generallyidentical (e.g., nominally identical within manufacturing tolerances) inmaterial and/or structural configuration. In other embodiments, thefirst, second, and third fibers 2008, 2012, 2014 can be generallyidentical (e.g., nominally identical within manufacturing tolerances) inmaterial and/or structural configuration relative to each other and thespacer fibers 2016 can be different relative thereto. For example, incertain embodiments, the first, second, third fibers 2008, 2012, 2014,can be multifilament fibers, and the spacer fibers 2016 can bemonofilament fibers. As such, aside from the general overall shape, thespecific structural configuration of each of the first fibers 2008, thesecond fibers 2012, the third fibers 2014, and the spacer fibers 2016 isnot shown.

In certain embodiments, the first fibers 2008 can be formed of lowfriction fibers (e.g., monofilament fibers) that are knitted or woven toeffect a substantiality smooth pattern to help retain the adjunct 2000on a top or deck surface on a cartridge when tissue slides across theadjunct 2000, for example, when the adjunct 2000 is being placed at thestapling site. As such, employing low friction fibers within a top layer(e.g., tissue-contacting layer) of an adjunct can minimize the frictionthat would otherwise be created between the tissue and adjunct as thetissue slides across the adjunct prior to staple deployment.

As further shown, the bottom layer 2004 includes fourth fibers 2019 thatcan be configured to increase the friction between the adjunct 2000 anda top or deck surface of a cartridge. This can help retain the adjunct2000 to the cartridge prior to staple deployment. The fourth fibers 2019can have a variety of configurations. For example, in some embodiments,the fourth fibers can be multifilament fibers. As such, aside from thegeneral overall shape, the specific structural configuration of thefourth fibers 2019 is not shown. Further, for sake of simplicity, onlyone fourth fiber 2019 is being illustrated.

The spacer fibers 2016 are interconnected within the first fibers 2008at first and second interconnections 2018, 2022 within the top layer2002, and the spacer fibers 2016 are interconnected with at least thesecond and third fibers 2012, 2014 at third and fourth interconnections2020, 2024 within the bottom layer 2004. As such, this interactionbetween the top and bottom layers 2002, 2004 with that of the core layer2006 secures the top layer 2002 to the bottom layer 2004. Further, theportions of spacer fibers that form the core layer 2006 are arranged insuch a manner to form standing fibers 2026. The standing fibers 2026 canbe have a variety of orientations within the core layer 2006, such as agenerally columnar configuration, as shown, meaning they are generallyoriented in adjacent columns. The standing fibers 2026 can be configuredto bend or compress in response to force being applied to the adjunct2000.

As shown in FIG. 20, the interconnections 2018, 2020, and 2022, 2024 canbe identical between the top layer 2002 and the bottom layer 2004. Theinterconnections 2018, 2020 are represented as tight knots, with thespacer fibers 2016 wrapping around the first fibers 2008 of the toplayer 2002 multiple times, while also wrapping around the second andthird fibers 2012, 2014 of the bottom layer 2004. In some embodiments,even though the interconnections 2018, 2020 are depicted as tight knotsformed by wrapping the spacer fibers 2016 around the first, second, andthird fibers 2008, 2012, 2014, other types of tight knots for theinterconnections 2018, 2020 can be used, such as any knot that preventssliding of the spacer fibers 2016 to slide along the first, second, andthird fibers 2008, 2012, 2014.

Additionally, the interconnections 2022, 2024 are represented as looseknots, with the spacer fibers 2016 passing through the first fibers 2008of the top layer 2002 for a single pass, while also passing through thesecond and third fibers 2012, 2014 of the bottom layer 2004 for a singlepass. In some embodiments, even though the interconnections 2022, 2024are depicted as loose knots formed by wrapping the spacer fibers 2016around the first, second, and third fibers 2008, 2012, 2014, other typesof loose knots for the interconnections 2022, 2024 can be used, such asany knot that prevents sliding of the spacer fibers 2016 to slide alongthe first, second, and third fibers 2008, 2012, 2014.

Due to the presence of two different types of interconnections, theadjunct 2000 can have a first compression zone 2028 and a secondcompression zone 2030. Each compression zone can have a differentstiffness when compressed, even though both compression zones aremanufactured from the same fibers. This is because when the adjunct 2000is compressed, the interconnections 2018, 2020 inhibit the spacer fibers2016 from sliding along the first, second, and third fibers 2008, 2012,2014, whereas, in contrast, the interconnections 2022, 2024 allow thespacer fibers 2016 to slide along the first, second, and third fibers2008, 2012, 2014. As such, each different compression zone 2028, 2030has a respective stiffness such that the adjunct 2000 can have avariable compression strength, for example, along its width (e.g., in ay-direction).

In certain embodiments, the spacer fibers can interact with at least aportion of the remaining fibers of the bottom layer (e.g.,cartridge-contacting layer) of an adjunct in such a way that allows thespacer fibers to extend beyond the remaining fibers (e.g., in the formof loops) when the adjunct is compressed. Alternatively, or in addition,the spacer fibers can interact with at least a portion of the remainingfibers of the top layer (e.g., tissue-contacting layer) of an adjunct insuch a way that allows the spacer fibers to extend beyond the remainingfibers (e.g., in the form of loops) when the adjunct is compressed.

In addition to fiber connectivity, the overall compression behavior ofan adjunct can at least partially depend on the type of spacer fibersincorporated therein. As such, a desired compression behavior of theadjunct can be effected by at least incorporating spacer fibers having aparticular structural configuration (e.g., monofilament ormultifilament) and/or dimensions (e.g., diameter), and/or a particularcompositional make-up (e.g., a first polymeric material having a lowmodulus of elasticity, a second polymeric material having a high modulusof elasticity, or a blend of two or more polymeric materials). Further,the compression behavior can be a function of the orientation of theportions of the spacer fibers within a core or intermediate layer of anadjunct (e.g., the direction the standing fibers extend relative to thelongitudinal axis of the adjunct).

In some embodiments, different spacer fibers can be incorporated intodifferent portions within the adjunct to effect different compressionzones within the adjunct. For example, a first type of spacer fiber(e.g., first spacer fibers) can be selected to create a firstcompression zone and a second type of spacer fiber (e.g., second spacerfibers) that differs from the first type of spacer fiber can be selectedto create a second compression zone. The first type of fiber can differfrom the second type of fiber in structure (e.g., structure type, e.g.,monofilament or multifilament, and/or in dimension, e.g., height and/ordiameter) and/or composition. As such, the first compression zone has afirst compression strength and the second compression zone has a secondcompression strength that is different than the second compressionstrength. As a result, the adjunct has a varied compression strength.

For example, the first compression zone can have a greater compressionstrength than the second compression zone, and therefore the firstcompression zone can be more stiff. In use, the first compression zonecan at least partially overlap with a longitudinal slot formed in thecartridge which is configured to receive a cutting member and the secondcompression zone can at least partially overlap with staple cavitiesdefined in the cartridge. Such an arrangement can facilitate thetransection of the adjunct while providing desirable tissue thicknesscompensation properties within the staples that capture the adjunctagainst the tissue. In certain instances, the second compression canalso partially overlap with one or more portions of the longitudinalslot. In one embodiment, the second compression zone can be theproximate-most zone to the beginning and/or end of the longitudinalslot.

FIGS. 21A-21B is an exemplary embodiment of a knitted adjunct 2100having two different types of spacer fibers. The adjunct 2100 includesfirst fibers 2102, second fibers 2104, first spacer fibers 2106, andsecond, different spacer fibers 2108 that are intertwined to form a toplayer 2110 (e.g., a tissue-contacting layer), a bottom layer 2112 (e.g.,a cartridge-contacting layer) and an intermediate layer 2114 that ispositioned between the top and bottom layers 2110, 2112. As shown inFIG. 21A, the first spacer fibers 2106 are concentrated within a centerportion of the intermediate layer 2114 (represented as a dotted box 2114a) and define a first compression zone of the adjunct 2100. The secondspacer fibers 2108 are concentrated in the remaining portion of theintermediate layer 2114 and define a second compression zone within theadjunct 2100.

The first fibers 2102, the second fibers 2104, the first spacer fibers2106, and the second spacer fibers 2108 can have a variety ofconfigurations. For example, in some embodiments, the first fibers 2102and the second fibers 2104 can be generally identical (e.g., nominallyidentical within manufacturing tolerances) in compositional makeup(e.g., formed of the same material(s)), dimension(s) (e.g., heightand/or diameter), and/or in structural configuration (e.g., monofilamentor multifilament). In other embodiments, the first and second fibers2102, 2104 can be different. Further, the first fibers and/or secondfibers can be the same as the first spacer fibers or the second spacerfibers. In some embodiments, the first fibers 2102, the second fibers2104, the first spacer fibers 2106, and/or the second spacer fibers 2108can be monofilament fibers. In other embodiments, the first fibers 2102,the second fibers 2104, the first spacer fibers 2106, and/or the secondspacer fibers 2108 can be monofilament fibers. In certain embodiments,the first fibers 2102, the second fibers 2104, and the first spacerfibers 2106 can be monofilament fibers and the second spacer fibers 2108are multifilament fibers. As such, aside from the general overall shape,the specific structural configuration of the first fibers 2102, thesecond fibers 2104, the first spacer fibers 2106, and the second spacerfibers 2108 are not shown.

In some embodiments, the first fibers 2102 of the top layer 2110 and/orsecond fibers 2104 of the bottom layer 2112 can be knitted in arespective predetermined pattern. In certain embodiments, thepredetermined pattern of the first fibers 2102 within the top layer 2110and the predetermined pattern of the second fibers 2104 of the bottomlayer 2112 can be generally identical (e.g., nominally identical withinmanufacturing tolerances), whereas in other embodiments, thepredetermined patterns can be different. Further, in some embodiments,the fiber density of the top layer 2110 can be different than the fiberdensity of the bottom layer 2112. While the first fibers 2102 of the toplayer 2110 and the second fibers 2104 of the bottom layer 2112 can eachbe knitted in various patterns, in certain embodiments, the first fibers2102 can be knitted into a first Raschel knit pattern and the secondfibers 2104 can be knitted into a second Raschel knit pattern that isthe same or different than the first Rachel knit pattern. A personskilled in the art will appreciate that the first fibers 2102 and thesecond fibers 2104 can be randomly or repeatedly knitted or woven withinthe top and bottom layers 2110, 2112, respectively. As such, and forsake of simplicity, the top and bottom layers 2110, 2112 are generallyillustrated, and thus the specific structural configurations of the topand bottom layers 2110, 2112 are not limited to what is depicted in thefigures.

As shown in FIGS. 21A-21B, the portions of the first spacer fibers 2106and the portions of the second spacer fibers 2108 that extend betweenthe top and bottom layers 2110, 2112 form the intermediate layer 2114.While these portions can have a variety of configurations, in thisillustrated embodiment, they are arranged in a generally columnarconfiguration, meaning they are generally oriented in adjacent columns.The compression behavior of the adjunct 2100 can therefore bepredominately driven by the buckling properties of the first and secondspacer fibers 2106, 2108.

As further shown, the first compression zone 2114 a is completelybordered by the second compression zone, and therefore the intendedcut-line C_(L) of the adjunct 2100 is defined across the first andsecond compression zones and along the longitudinal axis L_(A) of theadjunct 2100. In this illustrated embodiment, the majority of theintended cut-line C_(L) is defined by the first compression zone 2114 a,and therefore can be configured to be stiffer, and thus exhibit a higherresistance to compression, compared to the second compression zone. Forexample, the first spacer fibers 2106 can be monofilament fibers and thesecond spacer fibers 2108 can be multifilament fibers. Thus, theresulting adjunct 2100 can have a variable compression strength in alateral direction (e.g., the y-direction) relative to the cut-line C_(L)of the adjunct 2100. Further, the beginning and end of the cut-line CLis defined by the second compression zone, which can therefore makecutting of the adjunct 2100 easier.

In some embodiments, the bottom layer 2112 can also be formed of one ormore additional fibers 2116, as shown in more detail FIG. 21B. While theone or more additional fibers 2116 can have a variety of configurations,in this illustrated embodiment, the one or more additional fibers areinterconnected within the bottom layer 2112 in such a way to form loops(e.g., traction loops) that provide traction against a top or decksurface of a cartridge to thereby help retain the adjunct to thecartridge prior to staple deployment. Alternatively, or in addition, theone or more additional fibers 2116 can be incorporated into the adjunctfor purposes of thermoforming or bonding the adjunct to a cartridge. Theone or more additional fibers 2116 can be multifilament or monofilamentfibers. In one embodiment, the one or more additional fibers 2116 aremultifilament fibers. In certain embodiments, the one or more additionalfibers 2116 can include at least two first and second additional fibers,in which the first additional fiber differs from the second additionalfiber in compositional makeup (e.g., formed of the same material(s)),dimension(s) (e.g., height and/or diameter) and/or in structuralconfiguration (e.g., monofilament or multifilament).

The devices disclosed herein can be designed to be disposed of after asingle use, or they can be designed to be used multiple times. In eithercase, however, the device can be reconditioned for reuse after at leastone use. Reconditioning can include any combination of the steps ofdisassembly of the device, followed by cleaning or replacement ofparticular pieces and subsequent reassembly. In particular, the devicecan be disassembled, and any number of the particular pieces or parts ofthe device can be selectively replaced or removed in any combination.Upon cleaning and/or replacement of particular parts, the device can bereassembled for subsequent use either at a reconditioning facility, orby a surgical team immediately prior to a surgical procedure. Thoseskilled in the art will appreciate that reconditioning of a device canutilize a variety of techniques for disassembly, cleaning/replacement,and reassembly. Use of such techniques, and the resulting reconditioneddevice, are all within the scope of the present application.

Further, in the present disclosure, like-named components of theembodiments generally have similar features, and thus within aparticular embodiment each feature of each like-named component is notnecessarily fully elaborated upon. Additionally, to the extent thatlinear or circular dimensions are used in the description of thedisclosed systems, devices, and methods, such dimensions are notintended to limit the types of shapes that can be used in conjunctionwith such systems, devices, and methods. A person skilled in the artwill recognize that an equivalent to such linear and circular dimensionscan easily be determined for any geometric shape. Sizes and shapes ofthe systems and devices, and the components thereof, can depend at leaston the anatomy of the subject in which the systems and devices will beused, the size and shape of components with which the systems anddevices will be used, and the methods and procedures in which thesystems and devices will be used.

It will be appreciated that the terms “proximal” and “distal” are usedherein with reference to a user, such as a clinician, gripping a handleof a device. Other spatial terms such as “front” and “rear” similarlycorrespond respectively to distal and proximal. It will be furtherappreciated that for convenience and clarity, spatial terms such as“vertical” and “horizontal” are used herein with respect to thedrawings. However, surgical devices are used in many orientations andpositions, and these spatial terms are not intended to be limiting andabsolute.

Values or ranges may be expressed herein as “about” and/or from/of“about” one particular value to another particular value. When suchvalues or ranges are expressed, other embodiments disclosed include thespecific value recited and/or from/of the one particular value toanother particular value. Similarly, when values are expressed asapproximations, by the use of antecedent “about,” it will be understoodthat here are a number of values disclosed therein, and that theparticular value forms another embodiment. It will be further understoodthat there are a number of values disclosed therein, and that each valueis also herein disclosed as “about” that particular value in addition tothe value itself In embodiments, “about” can be used to mean, forexample, within 10% of the recited value, within 5% of the recited valueor within 2% of the recited value.

For purposes of describing and defining the present teachings, it isnoted that unless indicated otherwise, the term “substantially” isutilized herein to represent the inherent degree of uncertainty that maybe attributed to any quantitative comparison, value, measurement, orother representation. The term “substantially” is also utilized hereinto represent the degree by which a quantitative representation may varyfrom a stated reference without resulting in a change in the basicfunction of the subject matter at issue.

One skilled in the art will appreciate further features and advantagesof the invention based on the above-described embodiments. Accordingly,the invention is not to be limited by what has been particularly shownand described, except as indicated by the appended claims. Allpublications and references cited herein are expressly incorporatedherein by reference in their entirety. Any patent, publication, orinformation, in whole or in part, that is said to be incorporated byreference herein is only to the extent that the incorporated materialdoes not conflict with existing definitions, statements, or otherdisclosure material set forth in this document. As such the disclosureas explicitly set forth herein supersedes any conflicting materialincorporated herein by reference.

What is claimed is:
 1. An adjunct for use with a surgical staplecartridge, the adjunct comprising: a first knitted layer having firstfibers, the first knitted layer extending from a first top surface to afirst bottom surface with the first top surface defining at least aportion of a tissue-contacting surface of the adjunct, a second knittedlayer having second fibers, the second knitted layer extending from asecond top surface to a second bottom surface with the second topsurface defining at least a portion of a cartridge-contacting surface ofthe knitted adjunct; and a plurality of recesses extending into anddefined within the second knitted layer, the plurality of recesses beingarranged in a predefined pattern that coincides with a plurality ofattachment features extending outward from a top surface of a cartridgesuch that each recess of the plurality of recesses is configured toengage with at least a portion of at least one attachment feature toform a friction fit therebetween to thereby retain the adjunct on thecartridge prior to staple deployment.
 2. The adjunct of claim 1, whereinat least one of the first fibers and the second fibers are multifilamentfibers.
 3. The adjunct of claim 1, wherein further comprising and spacerfibers intertwined with and extending between the first and secondknitted layers to thereby connect the layers together.
 4. The adjunct ofclaim 3, wherein the spacer fibers are monofilament fibers.
 5. Theadjunct of claim 1, wherein each recess of the plurality of recesses isconically shaped.
 6. A stapling assembly for use with a surgicalstapler, comprising: a cartridge extending from a top surface to abottom surface that is opposite the top surface, the top surface being atissue-facing surface with a plurality of attachment features projectingtherefrom; a plurality of staples disposed within the cartridge, theplurality of staples being configured to be deployed into tissue; and aknitted adjunct configured to be releasably retained on the cartridgesuch that the adjunct can be attached to tissue by the plurality ofstaples in the cartridge, the adjunct comprising first and secondknitted outer layers formed of fibers, and spacer fibers intertwinedwith and extending between the first and second knitted outer layers tothereby connect the layers together, the second knitted outer layerhaving a plurality of preformed recesses defined therein, each recessbeing configured to receive and engage at least a portion of at leastone extension feature of the plurality of attachment features to therebyretain the adjunct on the cartridge prior to staple deployment.
 7. Thestapling assembly of claim 6, wherein each extension feature has aconical-shape with a first maximum diameter, and wherein each recess hasan inverted conical-shape with a second maximum diameter that is lessthan the first maximum diameter.
 8. The stapling assembly of claim 6,wherein each extension feature has a conical-shape with a first maximumdiameter, and wherein each recess has an inverted conical-shape with asecond maximum diameter that is greater than the first maximum diameter.9. The stapling assembly of claim 6, wherein at least one recess of theplurality of recesses has a perimeter defined by a melted portion of thefibers of the second knitted outer layer.
 10. The stapling assembly ofclaim 6, wherein at least one recess of the plurality of recesses has aperimeter defined by knitted fibers of the second knitted outer layer.11. The stapling assembly of claim 6, wherein at least one recess of theplurality of recesses has minimum diameter that is less than a diameterof a staple leg of at least one staple of the plurality of staples. 12.The stapling assembly of claim 6, wherein at least one recess of theplurality of recesses has a maximum diameter that is greater than amaximum diameter of at least one extension feature.
 13. The staplingassembly of claim 6, wherein the fibers of at least one of the firstouter knitted layer and second outer knitted layer are multifilamentfibers.
 14. The stapling assembly of claim 6, wherein the spacer fibersare monofilament fibers.
 15. A stapling assembly for use with a surgicalstapler, comprising: a cartridge with a plurality of conically shapedprojections coupled to and extending outward therefrom; a knittedadjunct configured to be releasably retained on the cartridge such thatthe adjunct can be attached to tissue by a plurality of staples disposedwithin the cartridge, the knitted adjunct comprising a first knittedlayer having first fibers, the first knitted layer extending from afirst top surface to a first bottom surface with the first top surfacedefining at least a portion of a tissue-contacting surface of theadjunct, a second knitted layer having second fibers, the second knittedlayer extending from a second top surface to a second bottom surfacewith the second top surface defining at least a portion of acartridge-contacting surface of the adjunct, and spacer fibersintertwined with the first and second fibers to connect the firstknitted layer with the second knitted layer, wherein portions of thespacer fibers extend between the first and second layers in a generallycolumnar configuration, and a plurality of conically shaped recessesextending into and defined within the second knitted layer, each recessbeing configured to receive and engage at least a portion of at leastone conically shaped projection of the plurality of conically shapedprojections to thereby retain the adjunct on the cartridge prior tostaple deployment
 16. The stapling assembly of claim 15, wherein eachrecess of the plurality of recesses has a tapering diameter thatdecreases as the recess extends into the second knitted layer.
 17. Thestapling assembly of claim 15, wherein at least one recess of theplurality of recesses has a perimeter defined by a melted portion of thesecond fibers.
 18. The stapling assembly of claim 15, wherein eachrecess of the plurality of recesses has a perimeter defined by knittedsecond fibers.
 19. The stapling assembly of claim 15, wherein eachrecess of the plurality of recesses has a minimum diameter that is lessthan a diameter of a staple leg of each of the plurality of staples. 20.The stapling assembly of claim 15, wherein at least one of the firstfibers and the second fibers are multifilament fibers.
 21. The staplingassembly of claim 15, wherein the spacer fibers are monofilament fibers.